hsp-6

UniProt ID: P11141
Organism: Caenorhabditis elegans
Review Status: COMPLETE
๐Ÿ“ Provide Detailed Feedback

Gene Description

HSP-6 is the C. elegans mitochondrial HSP70 chaperone (mtHSP70/mortalin ortholog) that functions as the primary ATP-dependent chaperone in the mitochondrial matrix. It is essential for mitochondrial protein import, serving as the import motor that drives translocation of precursor proteins across the inner membrane. HSP-6 also participates in protein folding within the matrix and is involved in iron-sulfur cluster biogenesis. The hsp-6 gene is a canonical marker of the mitochondrial unfolded protein response (UPR-mt), with hsp-6p::GFP being the standard reporter for UPR-mt activation. Expression is strongly induced by mitochondrial proteotoxic stress in an ATFS-1-dependent manner. Knockdown of HSP-6 causes reduced ATP levels, abnormal mitochondrial morphology, and progeria-like phenotypes including shortened lifespan.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005737 cytoplasm
IBA
GO_REF:0000033 		KEEP AS NON CORE
Summary: IBA annotation indicating cytoplasmic localization based on phylogenetic inference. While some HSP70 family members have cytoplasmic pools, HSP-6 is specifically the mitochondrial HSP70 with a mitochondrial transit peptide (residues 1-27) and is experimentally localized to mitochondria.
Reason: HSP-6 has an N-terminal mitochondrial transit peptide (UniProt FT TRANSIT 1..27) and is characterized as the mitochondrial matrix HSP70. While precursor protein may transiently exist in cytoplasm before import, the functional protein is mitochondrial. The IBA annotation likely reflects the broader HSP70 family distribution rather than HSP-6 specifically. However, this annotation is not incorrect as the precursor does exist in the cytoplasm before mitochondrial import.
Supporting Evidence:
PMID:17189267
HSP-6 (hsp70F) is a nematode orthologue of mthsp70.
GO:0005739 mitochondrion
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for mitochondrial localization based on phylogenetic inference from HSP70 family orthologs. This is strongly supported by experimental evidence.
Reason: HSP-6 is the C. elegans mitochondrial HSP70 (mtHSP70). UniProt annotation indicates subcellular location as mitochondrion and the protein has an N-terminal mitochondrial transit peptide. This is further confirmed by IDA evidence from PMID:17189267.
Supporting Evidence:
PMID:17189267
Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells.
GO:0016887 ATP hydrolysis activity
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for ATPase activity based on phylogenetic inference. HSP70 family chaperones universally require ATP hydrolysis for their chaperone function, driving conformational changes that mediate substrate binding and release.
Reason: HSP-6 contains the canonical HSP70 ATPase nucleotide-binding domain (IPR043129, Pfam HSP70). ATP hydrolysis is essential for HSP70 chaperone function, driving the conformational changes that allow substrate binding and release. For mtHSP70 specifically, ATP hydrolysis powers the import motor function. UniProt lists ATP-binding as a keyword.
Supporting Evidence:
file:worm/hsp-6/hsp-6-deep-research-falcon.md
HSP-6/mtHSP70 functions as an ATP-dependent mitochondrial chaperone supporting protein import and folding in the matrix [editorial summary of deep research]
GO:0031072 heat shock protein binding
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation indicating HSP-6 binds other heat shock proteins. This is consistent with HSP70 family function, as mtHSP70 works in concert with HSP60/HSP10 chaperonin system and co-chaperones.
Reason: HSP70 family members functionally interact with co-chaperones and other chaperones. In the mitochondrial matrix, mtHSP70 cooperates with HSP-60 (GroEL homolog) and DNJ-type co-chaperones. The IBA annotation is phylogenetically sound.
Supporting Evidence:
PMID:17189267
Knockdown of HSP-6 by RNA interference in young adult nematodes caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal mitochondrial morphology and lower ATP levels.
GO:0044183 protein folding chaperone
IBA
GO_REF:0000033 		MODIFY
Summary: IBA annotation for protein folding chaperone activity. This is a core function of HSP70 family proteins, though GO:0140662 (ATP-dependent protein folding chaperone) would be more specific.
Reason: While GO:0044183 is correct, the more specific term GO:0140662 (ATP-dependent protein folding chaperone) better describes HSP-6 function as an ATP-dependent HSP70 chaperone. HSP70 chaperones specifically use ATP hydrolysis to drive conformational changes for substrate binding and release.
Supporting Evidence:
PMID:15280428
Protein folding in the mitochondria is assisted by nuclear-encoded compartment-specific chaperones but regulation of the expression of their encoding genes is poorly understood.
GO:0016226 iron-sulfur cluster assembly
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for iron-sulfur cluster assembly based on phylogenetic inference. Mitochondrial HSP70 (HSPA9/mortalin in mammals) plays a documented role in Fe-S cluster biogenesis as part of the mitochondrial iron-sulfur cluster assembly machinery.
Reason: Mitochondrial HSP70 proteins are established components of the Fe-S cluster assembly pathway. In the mitochondrial matrix, mtHSP70 works with scaffold proteins (like ISCU) and cochaperones to facilitate Fe-S cluster assembly and transfer. This is a conserved function across eukaryotes.
GO:0042026 protein refolding
IBA
GO_REF:0000033 		ACCEPT
Summary: IBA annotation for protein refolding based on phylogenetic inference. HSP70 chaperones can assist in refolding of misfolded proteins, a key aspect of the stress response.
Reason: HSP70 family members are capable of assisting protein refolding, particularly under stress conditions. This annotation is consistent with HSP-6's induction as part of the mitochondrial unfolded protein response (UPR-mt), where it helps restore proteostasis in the matrix.
Supporting Evidence:
PMID:15280428
These observations support the existence of a mitochondrial unfolded protein response that couples mitochondrial chaperone gene expression to changes in the protein handling environment in the organelle.
GO:0000166 nucleotide binding
IEA
GO_REF:0000043 		KEEP AS NON CORE
Summary: IEA annotation based on UniProt keyword mapping for nucleotide binding. This is a parent term of ATP binding and is correct but less informative.
Reason: While technically correct (HSP-6 binds ATP), this is subsumed by the more specific GO:0005524 (ATP binding) annotation. It provides no additional information beyond the ATP binding annotation.
GO:0005524 ATP binding
IEA
GO_REF:0000120 		ACCEPT
Summary: IEA annotation for ATP binding based on automated annotation. HSP70 family proteins have a well-characterized nucleotide-binding domain that binds and hydrolyzes ATP.
Reason: HSP-6 contains the canonical HSP70 nucleotide-binding domain (ATPase_NBD, IPR043129) and ATP binding is essential for its chaperone function. UniProt lists ATP-binding as a keyword for this protein.
GO:0005739 mitochondrion
IEA
GO_REF:0000044 		ACCEPT
Summary: IEA annotation for mitochondrial localization based on UniProt subcellular location vocabulary mapping. This duplicates the IBA and IDA annotations but is independently derived.
Reason: Correct annotation. HSP-6 is the mitochondrial HSP70 with experimental evidence for mitochondrial localization. UniProt explicitly states subcellular location as mitochondrion.
GO:0006457 protein folding
IEA
GO_REF:0000002 		ACCEPT
Summary: IEA annotation for protein folding based on InterPro domain mapping. HSP70 family proteins assist protein folding as a core function.
Reason: Protein folding assistance is a core function of HSP70 chaperones. In the mitochondrial matrix, HSP-6 assists in folding of newly imported proteins and maintains proteostasis under stress conditions.
Supporting Evidence:
PMID:15280428
Protein folding in the mitochondria is assisted by nuclear-encoded compartment-specific chaperones but regulation of the expression of their encoding genes is poorly understood.
GO:0006950 response to stress
IEA
GO_REF:0000117 		KEEP AS NON CORE
Summary: IEA annotation for response to stress based on ARBA machine learning. While HSP-6 is stress-responsive, this term is very general. More specific terms exist.
Reason: While HSP-6 is indeed induced by stress (mitochondrial stress specifically), this term is too general. The protein is already annotated to GO:0034514 (mitochondrial unfolded protein response) which is more specific and informative. This annotation is not wrong but adds little beyond the more specific UPR-mt annotation.
Supporting Evidence:
PMID:15280428
hsp-6 and hsp-60 induction was specific to perturbed mitochondrial protein handling, as neither heat-shock nor endoplasmic reticulum stress nor manipulations that impair mitochondrial steps in intermediary metabolism or ATP synthesis activated the mitochondrial chaperone genes.
GO:0016887 ATP hydrolysis activity
IEA
GO_REF:0000002 		ACCEPT
Summary: IEA annotation for ATP hydrolysis activity based on InterPro domain mapping. Duplicates the IBA annotation but derived from domain analysis.
Reason: Correct annotation. HSP70 proteins have intrinsic ATPase activity essential for their chaperone function. The ATPase_NBD domain (IPR043129) is present in HSP-6.
GO:0051082 unfolded protein binding
IEA
GO_REF:0000002 		MODIFY
Summary: IEA annotation for unfolded protein binding based on InterPro domain mapping. HSP70 proteins bind to hydrophobic stretches in unfolded/misfolded proteins.
Reason: GO:0051082 is proposed for obsoletion. HSP-6 is a mitochondrial HSP70 foldase chaperone that binds unfolded clients and facilitates their folding in an ATP-dependent manner. The appropriate replacement term is GO:0044183 (protein folding chaperone).
Proposed replacements: protein folding chaperone
Supporting Evidence:
PMID:15280428
These observations support the existence of a mitochondrial unfolded protein response that couples mitochondrial chaperone gene expression to changes in the protein handling environment in the organelle.
GO:0005739 mitochondrion
IDA
PMID:17189267
Knockdown of mitochondrial heat shock protein 70 promotes pr... 		ACCEPT
Summary: IDA (direct assay) annotation for mitochondrial localization from Kimura et al. 2007. This provides experimental confirmation of mitochondrial localization.
Reason: Direct experimental evidence from PMID:17189267 demonstrates HSP-6 is the C. elegans mitochondrial HSP70. The study showed that HSP-6 knockdown affects mitochondrial morphology and reduces levels of mitochondrial proteins ATP-2 and HSP-60.
Supporting Evidence:
PMID:17189267
Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells.
GO:0034514 mitochondrial unfolded protein response
IEP
PMID:15280428
Compartment-specific perturbation of protein handling activa... 		ACCEPT
Summary: IEP (expression pattern) annotation indicating HSP-6 expression is induced during the mitochondrial unfolded protein response. This is the foundational study that established the UPR-mt concept using hsp-6 as a marker gene.
Reason: PMID:15280428 (Yoneda et al. 2004) is the landmark paper that defined the mitochondrial unfolded protein response in C. elegans. The study demonstrated that hsp-6 is specifically induced by mitochondrial protein folding stress but not by heat shock or ER stress. IEP is appropriate as induction pattern evidence.
Supporting Evidence:
PMID:15280428
These observations support the existence of a mitochondrial unfolded protein response that couples mitochondrial chaperone gene expression to changes in the protein handling environment in the organelle.
GO:0034514 mitochondrial unfolded protein response
IMP
PMID:15280428
Compartment-specific perturbation of protein handling activa... 		ACCEPT
Summary: IMP (mutant phenotype) annotation indicating HSP-6 participates in the mitochondrial unfolded protein response based on genetic evidence from Yoneda et al. 2004.
Reason: The same foundational study (PMID:15280428) used genetic perturbations to establish that hsp-6 is a functional component of the UPR-mt. RNAi of mitochondrial chaperones and proteases induced hsp-6 expression, demonstrating it is part of the compensatory UPR-mt pathway.
Supporting Evidence:
PMID:15280428
We found that the mitochondrial matrix HSP70 and HSP60 chaperones, encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively activated by perturbations that impair assembly of multi-subunit mitochondrial complexes or by RNAi of genes encoding mitochondrial chaperones or proteases, which lead to defective protein folding and processing in the organelle.
GO:0005759 mitochondrial matrix
IDA
PMID:15280428
Compartment-specific perturbation of protein handling activa... 		NEW
Summary: HSP-6 is specifically the mitochondrial matrix HSP70, functioning in the matrix compartment for protein import and folding.
Reason: HSP-6 is explicitly described as the mitochondrial matrix HSP70 chaperone. The more specific localization term GO:0005759 (mitochondrial matrix) would be more informative than the generic GO:0005739 (mitochondrion). The protein has a mitochondrial transit peptide and functions in the matrix where it acts as the import motor and folding chaperone.
Supporting Evidence:
PMID:15280428
We found that the mitochondrial matrix HSP70 and HSP60 chaperones, encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively activated by perturbations that impair assembly of multi-subunit mitochondrial complexes
GO:0030150 protein import into mitochondrial matrix
ISS
PMID:17189267
Knockdown of mitochondrial heat shock protein 70 promotes pr... 		NEW
Summary: mtHSP70 functions as the import motor that drives translocation of preproteins into the mitochondrial matrix.
Reason: PMID:17189267 explicitly states that mtHSP70 functions as a mitochondrial import motor. This is a well-established function of mtHSP70 family members across eukaryotes, where they provide the driving force for protein translocation through the TIM23 complex. Knockdown of HSP-6 reduces levels of nuclear-encoded mitochondrial proteins like ATP-2 and HSP-60, consistent with impaired import.
Supporting Evidence:
PMID:17189267
Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells.

Core Functions

HSP-6 is the C. elegans mitochondrial HSP70 family chaperone that uses ATP hydrolysis to drive conformational changes enabling substrate binding, folding assistance, and release. This ATP-dependent chaperone function is supported by domain analysis (ATPase_NBD, HSP70_peptide-bd_sf) and phylogenetic conservation with well-characterized mtHSP70 orthologs.

Molecular Function:
ATP-dependent protein folding chaperone
Directly Involved In:
protein folding
Cellular Locations:
mitochondrial matrix
Supporting Evidence:
  • PMID:15280428
    Protein folding in the mitochondria is assisted by nuclear-encoded compartment-specific chaperones but regulation of the expression of their encoding genes is poorly understood.
  • PMID:17189267
    Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells.

mtHSP70 functions as the mitochondrial import motor, providing the driving force for translocation of preproteins through the TIM23 translocase into the matrix. Knockdown of HSP-6 reduces levels of nuclear-encoded mitochondrial matrix proteins (ATP-2, HSP-60), consistent with impaired protein import.

Molecular Function:
unfolded protein binding
Directly Involved In:
protein import into mitochondrial matrix
Cellular Locations:
mitochondrial matrix
Supporting Evidence:
  • PMID:17189267
    Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells. HSP-6 (hsp70F) is a nematode orthologue of mthsp70.
  • PMID:17189267
    Knockdown of HSP-6 by RNA interference in young adult nematodes caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal mitochondrial morphology and lower ATP levels.

hsp-6 is the canonical marker gene for UPR-mt activation in C. elegans. The foundational study (PMID:15280428) demonstrated compartment-specific induction of hsp-6 by mitochondrial proteotoxic stress but not by heat shock or ER stress. hsp-6p::GFP is the standard reporter for UPR-mt studies, with induction being ATFS-1 dependent.

Molecular Function:
ATP hydrolysis activity
Directly Involved In:
mitochondrial unfolded protein response
Cellular Locations:
mitochondrial matrix
Supporting Evidence:
  • PMID:15280428
    hsp-6 and hsp-60 induction was specific to perturbed mitochondrial protein handling, as neither heat-shock nor endoplasmic reticulum stress nor manipulations that impair mitochondrial steps in intermediary metabolism or ATP synthesis activated the mitochondrial chaperone genes.

References

GO_REF:0000002
Gene Ontology annotation through association of InterPro records with GO terms
  • Automated annotation based on HSP70 family domain signatures
GO_REF:0000033
Annotation inferences using phylogenetic trees
  • Phylogenetic inference from characterized HSP70 family orthologs
GO_REF:0000043
Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  • Mapping from UniProt nucleotide-binding keyword
GO_REF:0000044
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
  • Mapping from UniProt subcellular location annotation
GO_REF:0000117
Electronic Gene Ontology annotations created by ARBA machine learning models
  • Machine learning-based stress response annotation
GO_REF:0000120
Combined Automated Annotation using Multiple IEA Methods
  • Integrated automated annotation for ATP binding
PMID:15280428
Compartment-specific perturbation of protein handling activates genes encoding mitochondrial chaperones.
  • Foundational paper establishing the mitochondrial unfolded protein response (UPR-mt) in C. elegans
    "These observations support the existence of a mitochondrial unfolded protein response that couples mitochondrial chaperone gene expression to changes in the protein handling environment in the organelle."
  • Demonstrated hsp-6 is specifically induced by mitochondrial protein folding stress
    "hsp-6 and hsp-60 induction was specific to perturbed mitochondrial protein handling, as neither heat-shock nor endoplasmic reticulum stress nor manipulations that impair mitochondrial steps in intermediary metabolism or ATP synthesis activated the mitochondrial chaperone genes."
  • Established hsp-6 and hsp-60 as mitochondrial matrix chaperone genes
    "We found that the mitochondrial matrix HSP70 and HSP60 chaperones, encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively activated by perturbations that impair assembly of multi-subunit mitochondrial complexes"
PMID:17189267
Knockdown of mitochondrial heat shock protein 70 promotes progeria-like phenotypes in caenorhabditis elegans.
  • Established HSP-6 as the C. elegans mtHSP70 ortholog with import motor function
    "Mitochondrial heat shock protein 70 (mthsp70) functions as a mitochondrial import motor and is essential in mitochondrial biogenesis and energy generation in eukaryotic cells. HSP-6 (hsp70F) is a nematode orthologue of mthsp70."
  • Demonstrated HSP-6 is essential for mitochondrial biogenesis
    "Knockdown of HSP-6 by RNA interference in young adult nematodes caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal mitochondrial morphology and lower ATP levels."
  • Linked HSP-6 reduction to progeria-like phenotypes and shortened lifespan
    "RNA interference-treated worms had lower motility, defects in oogenesis, earlier accumulation of autofluorescent material, and a shorter life span."
  • Showed HSP-6 levels decline at end of lifespan
    "The amount of HSP-6 became dramatically reduced at the expected mean life span in not only wild-type but also in long and short life span mutant worms (wild-type, daf-2, and daf-16)."
file:worm/hsp-6/hsp-6-deep-research-falcon.md
Deep research synthesis on C. elegans hsp-6 (HSP-6/mtHSP70)
  • HSP-6 is the C. elegans mitochondrial HSP70 chaperone central to mitochondrial proteostasis
  • hsp-6p::GFP is a validated ATFS-1-dependent reporter of UPR-mt activation
  • HSP-6 functions as an ATP-dependent chaperone supporting protein import and folding

Suggested Questions for Experts

Q: What specific co-chaperones (DNJ proteins) work with HSP-6 in C. elegans mitochondria?

Suggested experts: Mitochondrial proteostasis researchers, C. elegans geneticists

Q: Is HSP-6 involved in the folding of specific mitochondrial protein substrates, or is its substrate specificity broad?

Suggested experts: HSP70 chaperone biochemists, Mitochondrial protein import researchers

Q: What is the relative contribution of HSP-6 to import motor function versus post-import folding assistance?

Suggested experts: Mitochondrial protein import specialists, TIM23 complex researchers

Suggested Experiments

Experiment: Immunofluorescence or GFP-tagging to confirm mitochondrial matrix localization specifically (vs. outer membrane or intermembrane space)

Hypothesis: HSP-6 localizes specifically to the mitochondrial matrix compartment

Type: Subcellular localization

Experiment: Co-immunoprecipitation to identify specific protein interaction partners and substrates

Hypothesis: HSP-6 interacts with TIM23 complex components and specific mitochondrial substrate proteins

Type: Protein interaction analysis

Experiment: Genetic epistasis experiments with TIM23 complex components to confirm import motor function

Hypothesis: HSP-6 functions downstream of TIM23 in the protein import pathway

Type: Genetic epistasis

Tags

caeel-upr-stress

๐Ÿ“š Additional Documentation

Deep Research Falcon

(hsp-6-deep-research-falcon.md)

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organism: worm
gene_id: hsp-6
gene_symbol: hsp-6
uniprot_accession: P11141
protein_description: 'RecName: Full=Heat shock protein hsp-6 {ECO:0000305}; AltName:
Full=Heat shock 70 kDa protein F, mitochondrial {ECO:0000303|PubMed:2766926};
Flags: Precursor;'
gene_info: Name=hsp-6 {ECO:0000312|WormBase:C37H5.8}; Synonyms=hsp70f {ECO:0000303|PubMed:2766926},
mot-2 {ECO:0000312|WormBase:C37H5.8}; ORFNames=C37H5.8 {ECO:0000312|WormBase:C37H5.8};
organism_full: Caenorhabditis elegans.
protein_family: Belongs to the heat shock protein 70 family. .
protein_domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS.
(IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)
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Question

Gene Research for Functional Annotation

โš ๏ธ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

  • UniProt Accession: P11141
  • Protein Description: RecName: Full=Heat shock protein hsp-6 {ECO:0000305}; AltName: Full=Heat shock 70 kDa protein F, mitochondrial {ECO:0000303|PubMed:2766926}; Flags: Precursor;
  • Gene Information: Name=hsp-6 {ECO:0000312|WormBase:C37H5.8}; Synonyms=hsp70f {ECO:0000303|PubMed:2766926}, mot-2 {ECO:0000312|WormBase:C37H5.8}; ORFNames=C37H5.8 {ECO:0000312|WormBase:C37H5.8};
  • Organism (full): Caenorhabditis elegans.
  • Protein Family: Belongs to the heat shock protein 70 family. .
  • Key Domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS. (IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)

MANDATORY VERIFICATION STEPS:

  1. Check if the gene symbol "hsp-6" matches the protein description above
  2. Verify the organism is correct: Caenorhabditis elegans.
  3. Check if protein family/domains align with what you find in literature
  4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'hsp-6' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene hsp-6 (gene ID: hsp-6, UniProt: P11141) in worm.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

โš ๏ธ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

  • UniProt Accession: P11141
  • Protein Description: RecName: Full=Heat shock protein hsp-6 {ECO:0000305}; AltName: Full=Heat shock 70 kDa protein F, mitochondrial {ECO:0000303|PubMed:2766926}; Flags: Precursor;
  • Gene Information: Name=hsp-6 {ECO:0000312|WormBase:C37H5.8}; Synonyms=hsp70f {ECO:0000303|PubMed:2766926}, mot-2 {ECO:0000312|WormBase:C37H5.8}; ORFNames=C37H5.8 {ECO:0000312|WormBase:C37H5.8};
  • Organism (full): Caenorhabditis elegans.
  • Protein Family: Belongs to the heat shock protein 70 family. .
  • Key Domains: ATPase_NBD. (IPR043129); Chaperone_DnaK. (IPR012725); Heat_shock_70_CS. (IPR018181); HSP70_C_sf. (IPR029048); HSP70_peptide-bd_sf. (IPR029047)

MANDATORY VERIFICATION STEPS:

  1. Check if the gene symbol "hsp-6" matches the protein description above
  2. Verify the organism is correct: Caenorhabditis elegans.
  3. Check if protein family/domains align with what you find in literature
  4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'hsp-6' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene hsp-6 (gene ID: hsp-6, UniProt: P11141) in worm.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Comprehensive research report: C. elegans hsp-6 (UniProt: P11141)

Verification of target identity and context
- Identity and organism: The C. elegans hsp-6 gene encodes the mitochondrial Hsp70 chaperone (also known as mtHSP70/mortalin/Grp75), used widely as a canonical mitochondrial unfolded protein response (UPRmt) target and reporter gene in C. elegans, including via the hsp-6p::GFP transcriptional reporter; reporter activation is ATFS-1 dependent (PLOS Biology, 2021; URL: https://doi.org/10.1371/journal.pbio.3001302; published July 2021) (sladowska2021proteasomeactivitycontributes pages 5-7). A recent preprint explicitly equates HSP-6 with mtHSP70/mortalin in C. elegans, assaying HSP-6 protein by immunoblot (bioRxiv; URL: https://doi.org/10.1101/2023.09.07.556674; version posted December 2025) (li2025unveilingtheintercompartmental pages 8-12).
- Family/domains and localization: hsp-6 is a mitochondrial Hsp70-family chaperone localized to mitochondria; its promoter responds to mitochondrial import stress and UPRmt induction (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7). The same preprint frames HSP-6 as mtHSP70 with canonical chaperone roles and lipid interactions consistent with mitochondrial inner-membrane environments (bioRxiv, 2025; URL above) (li2025unveilingtheintercompartmental pages 12-15).

1) Key concepts and definitions
- HSP-6 is the C. elegans mitochondrial Hsp70 (mtHSP70) chaperone that assists mitochondrial proteostasis. In C. elegans, UPRmt is a retrograde stress pathway in which mitochondrial perturbations cause the transcription factor ATFS-1 to accumulate in the nucleus, inducing mitochondrial chaperones and proteases including hsp-6 (Cell Reports, 2024; URL: https://doi.org/10.1016/j.celrep.2024.114889; published November 2024) (sheng2024amitochondrialunfolded pages 16-18). Bibliometric synthesis identifies ATFS-1 import efficiency as a central regulatory node in C. elegans UPRmt and highlights conservation to mammalian ATF5 (Frontiers in Cell and Developmental Biology, 2023; URL: https://doi.org/10.3389/fcell.2023.1146963; published March 2023) (ye2023trendsinmitochondrial pages 11-11).
- hsp-6p::GFP is a canonical C. elegans reporter for UPRmt activation. Its induction is strongest in the intestine after mitochondrial perturbations, and is abolished by atfs-1 knockdown (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).

2) Primary function and pathway role
- Biochemical role: HSP-6/mtHSP70 functions as an ATP-dependent mitochondrial chaperone supporting protein import and folding in the matrix. Perturbing mitochondrial import triggers ATFS-1 nuclear signaling to induce hsp-6 expression (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7). A preprint further reinforces HSP-6โ€™s identity as mtHSP70 and connects its perturbation to mitochondrial lipid and ER stress signaling changes, consistent with chaperone roles at the mitochondriaโ€“ER interface (bioRxiv, 2025; URL above) (li2025unveilingtheintercompartmental pages 8-12, li2025unveilingtheintercompartmental pages 12-15).
- UPRmt regulation: Core UPRmt regulators include the mitochondrial ClpP protease, the matrix peptide exporter HAF-1, and the transcription factor ATFS-1; DVE-1 and chromatin remodeling factors act as modulators. This architecture and its links to longevity and immunity are synthesized in Cell Reports 2024 and cited foundational works (Cell Reports, 2024; URL above) (sheng2024amitochondrialunfolded pages 16-18). Field-level analyses emphasize ATFS-1โ€“dependent regulation and cross-species conservation (Frontiers in Cell and Developmental Biology, 2023; URL above) (ye2023trendsinmitochondrial pages 11-11).

3) Regulation and reporter usage
- ATFS-1 dependence: Mitochondrial import stress activates hsp-6 via ATFS-1; hsp-6p::GFP induction is abolished by atfs-1 knockdown (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).
- DVE-1 and UPRmt-independent roles: While DVE-1 is canonically associated with UPRmt, recent work shows DVE-1 also exerts longevity effects in ways separable from classical UPRmt signaling, refining interpretation of hsp-6 induction in longevity paradigms (Cell Reports, 2024; URL above) (sheng2024amitochondrialunfolded pages 16-18).
- Reporter practice: hsp-6p::GFP (and hsp-60p::GFP) are the most commonly used C. elegans transcriptional reporters for UPRmt activation, with atfs-1 required for their induction (bioRxiv, 2025; URL: https://doi.org/10.1101/2025.04.15.648933; posted April 2025) (kim2025transcriptomicanalysisof pages 1-2). Empirically, hsp-6p::GFP responds to mitochondrial perturbations (e.g., cox-5B, spg-7, mrps-5 RNAi) more robustly than to mild import perturbations (e.g., dnj-21 RNAi), showing graded sensitivity (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).

4) Recent developments and latest research (prioritizing 2023โ€“2024)
- UPRmt and longevity modulation beyond canonical axes: DVE-1 has UPRmt-independent roles in ciliary mutantsโ€™ longevity, indicating that hsp-6 induction is not a sole determinant of lifespan outcomes and highlighting complex network regulation of longevity (Cell Reports, 2024; URL above) (sheng2024amitochondrialunfolded pages 16-18).
- Field trend analyses (2004โ€“2022) emphasize the centrality of ATFS-1 regulation, emerging disease links, and translational interest. They contextualize the extensive use of hsp-6/hsp-6p::GFP in aging and disease-model studies (Frontiers in Cell and Developmental Biology, 2023; URL above) (ye2023trendsinmitochondrial pages 11-11).

5) Current applications and real-world implementations
- UPRmt reporter in vivo: hsp-6p::GFP is a standard readout for intestinal UPRmt activation under genetic (e.g., ETC subunit knockdown) and pharmacologic perturbations, with tissue-resolved fluorescence imaging and validation by ATFS-1 dependence (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).
- Cross-compartment proteostasis studies: Post-developmental hsp-6 (mtHSP70) knockdown has been used to probe mitochondriaโ€“ER stress crosstalk (MERSR), showing reduced ER stress and decreased polyglutamine aggregates; effects depend on VCP/cdc-48.1, indicating intersection with ERAD/UPS pathways (bioRxiv, 2025; URL: https://doi.org/10.1101/2023.09.07.556674) (li2025unveilingtheintercompartmental pages 19-26).
- Proteasomeโ€“mitochondria coordination: Mitochondrial import stress elicits proteasome activation and lifespan extension, situating hsp-6p::GFP as a reporter of mitochondrial stress in studies of cytosolic proteostasis coordination (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7, sladowska2021proteasomeactivitycontributes pages 29-30).

6) Expert opinions and authoritative synthesis
- Mechanistic synthesis: The 2024 Cell Reports study integrates primary literature to reaffirm ATFS-1โ€™s centrality and the roles of ClpP, HAF-1, DVE-1, and chromatin remodeling in UPRmt; it underscores that UPRmt activation can support cytoprotection and immunity but does not uniformly predict longevity (Cell Reports, 2024; URL above) (sheng2024amitochondrialunfolded pages 16-18).
- Field overview: Bibliometric analysis describes shifting emphasis from C. elegans to mammalian systems while maintaining ATFS-1 as a conceptual anchor and linking UPRmt to aging and diseases (Frontiers in Cell and Developmental Biology, 2023; URL above) (ye2023trendsinmitochondrial pages 11-11).

7) Quantitative data and specific findings
- Reporter induction: hsp-6p::GFP is robustly induced by canonical mitochondrial stressors (e.g., ETC subunit knockdown) and abolished by atfs-1 RNAi; mild import perturbation (dnj-21 RNAi) produces weaker, variable hsp-6 mRNA and reporter induction, strongest in intestine (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).
- Lifespan effects with mitochondrial import stress: Mild mitochondrial import stress (distinct from strong ETC disruption) can extend lifespan in C. elegans while coordinating proteasome activity; hsp-6p::GFP serves as the readout for UPRmt in these paradigms (PLOS Biology, 2021; URL above) (sladowska2021proteasomeactivitycontributes pages 5-7).
- hsp-6 knockdown phenotypes in proteostasis models: Post-developmental hsp-6 RNAi reduced poly-Q aggregation and improved motility; in one dataset, median lifespan in N2 increased from 22 days (empty vector) to 24 days with hsp-6 RNAi, and paralysis reductions in Aฮฒ or poly-Q models reached high significance (e.g., P<0.0001) (bioRxiv, 2025; URL: https://doi.org/10.1101/2023.09.07.556674) (li2025unveilingtheintercompartmental pages 19-26).

Conclusions and current understanding
- HSP-6 (UniProt P11141) is the C. elegans mitochondrial Hsp70 chaperone central to mitochondrial proteostasis, induced by ATFS-1 during UPRmt, and localized to mitochondria. hsp-6p::GFP is a validated, ATFS-1โ€“dependent reporter of UPRmt activation, widely used in studies of mitochondrial stress, proteostasis coordination, longevity, and immunity. Recent work refines the network, showing modulators such as DVE-1 can regulate longevity independently of canonical UPRmt, and that manipulating HSP-6 intersects with ER stress and aggregate handling, underscoring cross-organelle proteostasis (Cell Reports, 2024; PLOS Biology, 2021; Frontiers in Cell and Developmental Biology, 2023; bioRxiv, 2025) (sheng2024amitochondrialunfolded pages 16-18, sladowska2021proteasomeactivitycontributes pages 5-7, ye2023trendsinmitochondrial pages 11-11, li2025unveilingtheintercompartmental pages 19-26).

Notes on limitations and gaps
- Precise biochemical domain-level details (ATPase NBD, peptide-binding domain) and co-chaperone specificity in C. elegans were inferred from Hsp70 family knowledge and contextualized by the cited works as mitochondrial Hsp70 function; direct domain mapping for HSP-6 was not explicitly provided in the retrieved excerpts. When needed, hsp-6p::GFP quantitation and fold-induction values should be extracted from figure panels and supplement of reporter-based studies (e.g., Sladowska 2021) (sladowska2021proteasomeactivitycontributes pages 5-7).

References

  1. (sladowska2021proteasomeactivitycontributes pages 5-7): Maria Sladowska, Michaล‚ Turek, Min-Ji Kim, Krzysztof Drabikowski, Ben Hur Marins Mussulini, Karthik Mohanraj, Remigiusz A. Serwa, Ulrike Topf, and Agnieszka Chacinska. Proteasome activity contributes to pro-survival response upon mild mitochondrial stress in caenorhabditis elegans. PLOS Biology, 19:e3001302, Jul 2021. URL: https://doi.org/10.1371/journal.pbio.3001302, doi:10.1371/journal.pbio.3001302. This article has 31 citations and is from a highest quality peer-reviewed journal.

  2. (li2025unveilingtheintercompartmental pages 8-12): Jeson J Li, Nan Xin, Chunxia Yang, Larissa A Tavizon, Ruth Hong, Jina Park, Travis I Moore, Rebecca George Tharyan, Adam Antebi, and Hyun-Eui Kim. Unveiling the intercompartmental signaling axis: mitochondrial to er stress response (mersr) and its impact on proteostasis. bioRxiv, Dec 2025. URL: https://doi.org/10.1101/2023.09.07.556674, doi:10.1101/2023.09.07.556674. This article has 2 citations and is from a poor quality or predatory journal.

  3. (li2025unveilingtheintercompartmental pages 12-15): Jeson J Li, Nan Xin, Chunxia Yang, Larissa A Tavizon, Ruth Hong, Jina Park, Travis I Moore, Rebecca George Tharyan, Adam Antebi, and Hyun-Eui Kim. Unveiling the intercompartmental signaling axis: mitochondrial to er stress response (mersr) and its impact on proteostasis. bioRxiv, Dec 2025. URL: https://doi.org/10.1101/2023.09.07.556674, doi:10.1101/2023.09.07.556674. This article has 2 citations and is from a poor quality or predatory journal.

  4. (sheng2024amitochondrialunfolded pages 16-18): Yi Sheng, Adriana Abreu, Zachary Markovich, Pearl Ebea, Leah Davis, Eric Park, Peike Sheng, Mingyi Xie, Sung Min Han, and Rui Xiao. A mitochondrial unfolded protein response-independent role of dve-1 in longevity regulation. Cell Reports, 43:114889, Nov 2024. URL: https://doi.org/10.1016/j.celrep.2024.114889, doi:10.1016/j.celrep.2024.114889. This article has 2 citations and is from a highest quality peer-reviewed journal.

  5. (ye2023trendsinmitochondrial pages 11-11): Zelin Ye, Ruoning Chai, Yujie Luan, Yihang Du, Wenjing Xue, Shuqing Shi, Huaqin Wu, Yi Wei, Limei Zhang, and Yuanhui Hu. Trends in mitochondrial unfolded protein response research from 2004 to 2022: a bibliometric analysis. Frontiers in Cell and Developmental Biology, Mar 2023. URL: https://doi.org/10.3389/fcell.2023.1146963, doi:10.3389/fcell.2023.1146963. This article has 8 citations and is from a poor quality or predatory journal.

  6. (kim2025transcriptomicanalysisof pages 1-2): Juri Kim, Naibedya Dutta, Gilberto Garcia, and Ryo Higuchi-Sanabria. Transcriptomic analysis of mitohormesis associated with lifespan extension in caenorhabditis elegans. bioRxiv, Apr 2025. URL: https://doi.org/10.1101/2025.04.15.648933, doi:10.1101/2025.04.15.648933. This article has 0 citations and is from a poor quality or predatory journal.

  7. (li2025unveilingtheintercompartmental pages 19-26): Jeson J Li, Nan Xin, Chunxia Yang, Larissa A Tavizon, Ruth Hong, Jina Park, Travis I Moore, Rebecca George Tharyan, Adam Antebi, and Hyun-Eui Kim. Unveiling the intercompartmental signaling axis: mitochondrial to er stress response (mersr) and its impact on proteostasis. bioRxiv, Dec 2025. URL: https://doi.org/10.1101/2023.09.07.556674, doi:10.1101/2023.09.07.556674. This article has 2 citations and is from a poor quality or predatory journal.

  8. (sladowska2021proteasomeactivitycontributes pages 29-30): Maria Sladowska, Michaล‚ Turek, Min-Ji Kim, Krzysztof Drabikowski, Ben Hur Marins Mussulini, Karthik Mohanraj, Remigiusz A. Serwa, Ulrike Topf, and Agnieszka Chacinska. Proteasome activity contributes to pro-survival response upon mild mitochondrial stress in caenorhabditis elegans. PLOS Biology, 19:e3001302, Jul 2021. URL: https://doi.org/10.1371/journal.pbio.3001302, doi:10.1371/journal.pbio.3001302. This article has 31 citations and is from a highest quality peer-reviewed journal.

Citations

  1. sladowska2021proteasomeactivitycontributes pages 5-7
  2. li2025unveilingtheintercompartmental pages 8-12
  3. li2025unveilingtheintercompartmental pages 12-15
  4. sheng2024amitochondrialunfolded pages 16-18
  5. ye2023trendsinmitochondrial pages 11-11
  6. kim2025transcriptomicanalysisof pages 1-2
  7. li2025unveilingtheintercompartmental pages 19-26
  8. sladowska2021proteasomeactivitycontributes pages 29-30
  9. https://doi.org/10.1371/journal.pbio.3001302;
  10. https://doi.org/10.1101/2023.09.07.556674;
  11. https://doi.org/10.1016/j.celrep.2024.114889;
  12. https://doi.org/10.3389/fcell.2023.1146963;
  13. https://doi.org/10.1101/2025.04.15.648933;
  14. https://doi.org/10.1101/2023.09.07.556674
  15. https://doi.org/10.1371/journal.pbio.3001302,
  16. https://doi.org/10.1101/2023.09.07.556674,
  17. https://doi.org/10.1016/j.celrep.2024.114889,
  18. https://doi.org/10.3389/fcell.2023.1146963,
  19. https://doi.org/10.1101/2025.04.15.648933,

๐Ÿ“„ View Raw YAML

 
id: P11141
gene_symbol: hsp-6
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:6239
  label: Caenorhabditis elegans
description: HSP-6 is the C. elegans mitochondrial HSP70 chaperone (mtHSP70/mortalin
  ortholog) that functions as the primary ATP-dependent chaperone in the mitochondrial
  matrix. It is essential for mitochondrial protein import, serving as the import
  motor that drives translocation of precursor proteins across the inner membrane.
  HSP-6 also participates in protein folding within the matrix and is involved in
  iron-sulfur cluster biogenesis. The hsp-6 gene is a canonical marker of the mitochondrial
  unfolded protein response (UPR-mt), with hsp-6p::GFP being the standard reporter
  for UPR-mt activation. Expression is strongly induced by mitochondrial proteotoxic
  stress in an ATFS-1-dependent manner. Knockdown of HSP-6 causes reduced ATP levels,
  abnormal mitochondrial morphology, and progeria-like phenotypes including shortened
  lifespan.
existing_annotations:
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation indicating cytoplasmic localization based on phylogenetic
      inference. While some HSP70 family members have cytoplasmic pools, HSP-6 is
      specifically the mitochondrial HSP70 with a mitochondrial transit peptide (residues
      1-27) and is experimentally localized to mitochondria.
    action: KEEP_AS_NON_CORE
    reason: HSP-6 has an N-terminal mitochondrial transit peptide (UniProt FT TRANSIT
      1..27) and is characterized as the mitochondrial matrix HSP70. While precursor
      protein may transiently exist in cytoplasm before import, the functional protein
      is mitochondrial. The IBA annotation likely reflects the broader HSP70 family
      distribution rather than HSP-6 specifically. However, this annotation is not
      incorrect as the precursor does exist in the cytoplasm before mitochondrial
      import.
    supported_by:
    - reference_id: PMID:17189267
      supporting_text: HSP-6 (hsp70F) is a nematode orthologue of mthsp70.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for mitochondrial localization based on phylogenetic inference
      from HSP70 family orthologs. This is strongly supported by experimental evidence.
    action: ACCEPT
    reason: HSP-6 is the C. elegans mitochondrial HSP70 (mtHSP70). UniProt annotation
      indicates subcellular location as mitochondrion and the protein has an N-terminal
      mitochondrial transit peptide. This is further confirmed by IDA evidence from
      PMID:17189267.
    supported_by:
    - reference_id: PMID:17189267
      supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as
        a mitochondrial import motor and is essential in mitochondrial biogenesis
        and energy generation in eukaryotic cells.
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for ATPase activity based on phylogenetic inference. HSP70
      family chaperones universally require ATP hydrolysis for their chaperone function,
      driving conformational changes that mediate substrate binding and release.
    action: ACCEPT
    reason: HSP-6 contains the canonical HSP70 ATPase nucleotide-binding domain (IPR043129,
      Pfam HSP70). ATP hydrolysis is essential for HSP70 chaperone function, driving
      the conformational changes that allow substrate binding and release. For mtHSP70
      specifically, ATP hydrolysis powers the import motor function. UniProt lists
      ATP-binding as a keyword.
    supported_by:
    - reference_id: file:worm/hsp-6/hsp-6-deep-research-falcon.md
      supporting_text: HSP-6/mtHSP70 functions as an ATP-dependent mitochondrial chaperone
        supporting protein import and folding in the matrix [editorial summary of
        deep research]
- term:
    id: GO:0031072
    label: heat shock protein binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation indicating HSP-6 binds other heat shock proteins. This
      is consistent with HSP70 family function, as mtHSP70 works in concert with HSP60/HSP10
      chaperonin system and co-chaperones.
    action: ACCEPT
    reason: HSP70 family members functionally interact with co-chaperones and other
      chaperones. In the mitochondrial matrix, mtHSP70 cooperates with HSP-60 (GroEL
      homolog) and DNJ-type co-chaperones. The IBA annotation is phylogenetically
      sound.
    supported_by:
    - reference_id: PMID:17189267
      supporting_text: Knockdown of HSP-6 by RNA interference in young adult nematodes
        caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal
        mitochondrial morphology and lower ATP levels.
- term:
    id: GO:0044183
    label: protein folding chaperone
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for protein folding chaperone activity. This is a core
      function of HSP70 family proteins, though GO:0140662 (ATP-dependent protein
      folding chaperone) would be more specific.
    action: MODIFY
    reason: While GO:0044183 is correct, the more specific term GO:0140662 (ATP-dependent
      protein folding chaperone) better describes HSP-6 function as an ATP-dependent
      HSP70 chaperone. HSP70 chaperones specifically use ATP hydrolysis to drive conformational
      changes for substrate binding and release.
    proposed_replacement_terms:
    - id: GO:0140662
      label: ATP-dependent protein folding chaperone
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: Protein folding in the mitochondria is assisted by nuclear-encoded
        compartment-specific chaperones but regulation of the expression of their
        encoding genes is poorly understood.
- term:
    id: GO:0016226
    label: iron-sulfur cluster assembly
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for iron-sulfur cluster assembly based on phylogenetic
      inference. Mitochondrial HSP70 (HSPA9/mortalin in mammals) plays a documented
      role in Fe-S cluster biogenesis as part of the mitochondrial iron-sulfur cluster
      assembly machinery.
    action: ACCEPT
    reason: Mitochondrial HSP70 proteins are established components of the Fe-S cluster
      assembly pathway. In the mitochondrial matrix, mtHSP70 works with scaffold proteins
      (like ISCU) and cochaperones to facilitate Fe-S cluster assembly and transfer.
      This is a conserved function across eukaryotes.
    supported_by: []
- term:
    id: GO:0042026
    label: protein refolding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: IBA annotation for protein refolding based on phylogenetic inference.
      HSP70 chaperones can assist in refolding of misfolded proteins, a key aspect
      of the stress response.
    action: ACCEPT
    reason: HSP70 family members are capable of assisting protein refolding, particularly
      under stress conditions. This annotation is consistent with HSP-6's induction
      as part of the mitochondrial unfolded protein response (UPR-mt), where it helps
      restore proteostasis in the matrix.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: These observations support the existence of a mitochondrial
        unfolded protein response that couples mitochondrial chaperone gene expression
        to changes in the protein handling environment in the organelle.
- term:
    id: GO:0000166
    label: nucleotide binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: IEA annotation based on UniProt keyword mapping for nucleotide binding.
      This is a parent term of ATP binding and is correct but less informative.
    action: KEEP_AS_NON_CORE
    reason: While technically correct (HSP-6 binds ATP), this is subsumed by the more
      specific GO:0005524 (ATP binding) annotation. It provides no additional information
      beyond the ATP binding annotation.
    supported_by: []
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: IEA annotation for ATP binding based on automated annotation. HSP70 family
      proteins have a well-characterized nucleotide-binding domain that binds and
      hydrolyzes ATP.
    action: ACCEPT
    reason: HSP-6 contains the canonical HSP70 nucleotide-binding domain (ATPase_NBD,
      IPR043129) and ATP binding is essential for its chaperone function. UniProt
      lists ATP-binding as a keyword for this protein.
    supported_by: []
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: IEA annotation for mitochondrial localization based on UniProt subcellular
      location vocabulary mapping. This duplicates the IBA and IDA annotations but
      is independently derived.
    action: ACCEPT
    reason: Correct annotation. HSP-6 is the mitochondrial HSP70 with experimental
      evidence for mitochondrial localization. UniProt explicitly states subcellular
      location as mitochondrion.
    supported_by: []
- term:
    id: GO:0006457
    label: protein folding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation for protein folding based on InterPro domain mapping.
      HSP70 family proteins assist protein folding as a core function.
    action: ACCEPT
    reason: Protein folding assistance is a core function of HSP70 chaperones. In
      the mitochondrial matrix, HSP-6 assists in folding of newly imported proteins
      and maintains proteostasis under stress conditions.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: Protein folding in the mitochondria is assisted by nuclear-encoded
        compartment-specific chaperones but regulation of the expression of their
        encoding genes is poorly understood.
- term:
    id: GO:0006950
    label: response to stress
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: IEA annotation for response to stress based on ARBA machine learning.
      While HSP-6 is stress-responsive, this term is very general. More specific terms
      exist.
    action: KEEP_AS_NON_CORE
    reason: While HSP-6 is indeed induced by stress (mitochondrial stress specifically),
      this term is too general. The protein is already annotated to GO:0034514 (mitochondrial
      unfolded protein response) which is more specific and informative. This annotation
      is not wrong but adds little beyond the more specific UPR-mt annotation.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: hsp-6 and hsp-60 induction was specific to perturbed mitochondrial
        protein handling, as neither heat-shock nor endoplasmic reticulum stress nor
        manipulations that impair mitochondrial steps in intermediary metabolism or
        ATP synthesis activated the mitochondrial chaperone genes.
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation for ATP hydrolysis activity based on InterPro domain mapping.
      Duplicates the IBA annotation but derived from domain analysis.
    action: ACCEPT
    reason: Correct annotation. HSP70 proteins have intrinsic ATPase activity essential
      for their chaperone function. The ATPase_NBD domain (IPR043129) is present in
      HSP-6.
    supported_by: []
- term:
    id: GO:0051082
    label: unfolded protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: IEA annotation for unfolded protein binding based on InterPro domain
      mapping. HSP70 proteins bind to hydrophobic stretches in unfolded/misfolded
      proteins.
    action: MODIFY
    reason: GO:0051082 is proposed for obsoletion. HSP-6 is a mitochondrial HSP70
      foldase chaperone that binds unfolded clients and facilitates their folding in
      an ATP-dependent manner. The appropriate replacement term is GO:0044183
      (protein folding chaperone).
    proposed_replacement_terms:
    - id: GO:0044183
      label: protein folding chaperone
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: These observations support the existence of a mitochondrial
        unfolded protein response that couples mitochondrial chaperone gene expression
        to changes in the protein handling environment in the organelle.
- term:
    id: GO:0005739
    label: mitochondrion
  evidence_type: IDA
  original_reference_id: PMID:17189267
  review:
    summary: IDA (direct assay) annotation for mitochondrial localization from Kimura
      et al. 2007. This provides experimental confirmation of mitochondrial localization.
    action: ACCEPT
    reason: Direct experimental evidence from PMID:17189267 demonstrates HSP-6 is
      the C. elegans mitochondrial HSP70. The study showed that HSP-6 knockdown affects
      mitochondrial morphology and reduces levels of mitochondrial proteins ATP-2
      and HSP-60.
    supported_by:
    - reference_id: PMID:17189267
      supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as
        a mitochondrial import motor and is essential in mitochondrial biogenesis
        and energy generation in eukaryotic cells.
- term:
    id: GO:0034514
    label: mitochondrial unfolded protein response
  evidence_type: IEP
  original_reference_id: PMID:15280428
  review:
    summary: IEP (expression pattern) annotation indicating HSP-6 expression is induced
      during the mitochondrial unfolded protein response. This is the foundational
      study that established the UPR-mt concept using hsp-6 as a marker gene.
    action: ACCEPT
    reason: PMID:15280428 (Yoneda et al. 2004) is the landmark paper that defined
      the mitochondrial unfolded protein response in C. elegans. The study demonstrated
      that hsp-6 is specifically induced by mitochondrial protein folding stress but
      not by heat shock or ER stress. IEP is appropriate as induction pattern evidence.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: These observations support the existence of a mitochondrial
        unfolded protein response that couples mitochondrial chaperone gene expression
        to changes in the protein handling environment in the organelle.
- term:
    id: GO:0034514
    label: mitochondrial unfolded protein response
  evidence_type: IMP
  original_reference_id: PMID:15280428
  review:
    summary: IMP (mutant phenotype) annotation indicating HSP-6 participates in the
      mitochondrial unfolded protein response based on genetic evidence from Yoneda
      et al. 2004.
    action: ACCEPT
    reason: The same foundational study (PMID:15280428) used genetic perturbations
      to establish that hsp-6 is a functional component of the UPR-mt. RNAi of mitochondrial
      chaperones and proteases induced hsp-6 expression, demonstrating it is part
      of the compensatory UPR-mt pathway.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: We found that the mitochondrial matrix HSP70 and HSP60 chaperones,
        encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively
        activated by perturbations that impair assembly of multi-subunit mitochondrial
        complexes or by RNAi of genes encoding mitochondrial chaperones or proteases,
        which lead to defective protein folding and processing in the organelle.
- term:
    id: GO:0005759
    label: mitochondrial matrix
  evidence_type: IDA
  original_reference_id: PMID:15280428
  review:
    summary: HSP-6 is specifically the mitochondrial matrix HSP70, functioning in
      the matrix compartment for protein import and folding.
    action: NEW
    reason: HSP-6 is explicitly described as the mitochondrial matrix HSP70 chaperone.
      The more specific localization term GO:0005759 (mitochondrial matrix) would
      be more informative than the generic GO:0005739 (mitochondrion). The protein
      has a mitochondrial transit peptide and functions in the matrix where it acts
      as the import motor and folding chaperone.
    supported_by:
    - reference_id: PMID:15280428
      supporting_text: We found that the mitochondrial matrix HSP70 and HSP60 chaperones,
        encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively
        activated by perturbations that impair assembly of multi-subunit mitochondrial
        complexes
- term:
    id: GO:0030150
    label: protein import into mitochondrial matrix
  evidence_type: ISS
  original_reference_id: PMID:17189267
  review:
    summary: mtHSP70 functions as the import motor that drives translocation of preproteins
      into the mitochondrial matrix.
    action: NEW
    reason: PMID:17189267 explicitly states that mtHSP70 functions as a mitochondrial
      import motor. This is a well-established function of mtHSP70 family members
      across eukaryotes, where they provide the driving force for protein translocation
      through the TIM23 complex. Knockdown of HSP-6 reduces levels of nuclear-encoded
      mitochondrial proteins like ATP-2 and HSP-60, consistent with impaired import.
    supported_by:
    - reference_id: PMID:17189267
      supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as
        a mitochondrial import motor and is essential in mitochondrial biogenesis
        and energy generation in eukaryotic cells.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings:
  - statement: Automated annotation based on HSP70 family domain signatures
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings:
  - statement: Phylogenetic inference from characterized HSP70 family orthologs
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings:
  - statement: Mapping from UniProt nucleotide-binding keyword
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings:
  - statement: Mapping from UniProt subcellular location annotation
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings:
  - statement: Machine learning-based stress response annotation
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings:
  - statement: Integrated automated annotation for ATP binding
- id: PMID:15280428
  title: Compartment-specific perturbation of protein handling activates genes encoding
    mitochondrial chaperones.
  findings:
  - statement: Foundational paper establishing the mitochondrial unfolded protein
      response (UPR-mt) in C. elegans
    supporting_text: These observations support the existence of a mitochondrial unfolded
      protein response that couples mitochondrial chaperone gene expression to changes
      in the protein handling environment in the organelle.
    reference_section_type: ABSTRACT
  - statement: Demonstrated hsp-6 is specifically induced by mitochondrial protein
      folding stress
    supporting_text: hsp-6 and hsp-60 induction was specific to perturbed mitochondrial
      protein handling, as neither heat-shock nor endoplasmic reticulum stress nor
      manipulations that impair mitochondrial steps in intermediary metabolism or
      ATP synthesis activated the mitochondrial chaperone genes.
    reference_section_type: ABSTRACT
  - statement: Established hsp-6 and hsp-60 as mitochondrial matrix chaperone genes
    supporting_text: We found that the mitochondrial matrix HSP70 and HSP60 chaperones,
      encoded by the Caenorhabditis elegans hsp-6 and hsp-60 genes, were selectively
      activated by perturbations that impair assembly of multi-subunit mitochondrial
      complexes
    reference_section_type: ABSTRACT
- id: PMID:17189267
  title: Knockdown of mitochondrial heat shock protein 70 promotes progeria-like phenotypes
    in caenorhabditis elegans.
  findings:
  - statement: Established HSP-6 as the C. elegans mtHSP70 ortholog with import motor
      function
    supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as a
      mitochondrial import motor and is essential in mitochondrial biogenesis and
      energy generation in eukaryotic cells. HSP-6 (hsp70F) is a nematode orthologue
      of mthsp70.
    reference_section_type: ABSTRACT
  - statement: Demonstrated HSP-6 is essential for mitochondrial biogenesis
    supporting_text: Knockdown of HSP-6 by RNA interference in young adult nematodes
      caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal
      mitochondrial morphology and lower ATP levels.
    reference_section_type: ABSTRACT
  - statement: Linked HSP-6 reduction to progeria-like phenotypes and shortened lifespan
    supporting_text: RNA interference-treated worms had lower motility, defects in
      oogenesis, earlier accumulation of autofluorescent material, and a shorter life
      span.
    reference_section_type: ABSTRACT
  - statement: Showed HSP-6 levels decline at end of lifespan
    supporting_text: The amount of HSP-6 became dramatically reduced at the expected
      mean life span in not only wild-type but also in long and short life span mutant
      worms (wild-type, daf-2, and daf-16).
    reference_section_type: ABSTRACT
- id: file:worm/hsp-6/hsp-6-deep-research-falcon.md
  title: Deep research synthesis on C. elegans hsp-6 (HSP-6/mtHSP70)
  findings:
  - statement: HSP-6 is the C. elegans mitochondrial HSP70 chaperone central to mitochondrial
      proteostasis
  - statement: hsp-6p::GFP is a validated ATFS-1-dependent reporter of UPR-mt activation
  - statement: HSP-6 functions as an ATP-dependent chaperone supporting protein import
      and folding
core_functions:
- description: HSP-6 is the C. elegans mitochondrial HSP70 family chaperone that uses
    ATP hydrolysis to drive conformational changes enabling substrate binding, folding
    assistance, and release. This ATP-dependent chaperone function is supported by
    domain analysis (ATPase_NBD, HSP70_peptide-bd_sf) and phylogenetic conservation
    with well-characterized mtHSP70 orthologs.
  molecular_function:
    id: GO:0140662
    label: ATP-dependent protein folding chaperone
  directly_involved_in:
  - id: GO:0006457
    label: protein folding
  locations:
  - id: GO:0005759
    label: mitochondrial matrix
  supported_by:
  - reference_id: PMID:15280428
    supporting_text: Protein folding in the mitochondria is assisted by nuclear-encoded
      compartment-specific chaperones but regulation of the expression of their encoding
      genes is poorly understood.
  - reference_id: PMID:17189267
    supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as a
      mitochondrial import motor and is essential in mitochondrial biogenesis and
      energy generation in eukaryotic cells.
- description: mtHSP70 functions as the mitochondrial import motor, providing the
    driving force for translocation of preproteins through the TIM23 translocase into
    the matrix. Knockdown of HSP-6 reduces levels of nuclear-encoded mitochondrial
    matrix proteins (ATP-2, HSP-60), consistent with impaired protein import.
  molecular_function:
    id: GO:0051082
    label: unfolded protein binding
  directly_involved_in:
  - id: GO:0030150
    label: protein import into mitochondrial matrix
  locations:
  - id: GO:0005759
    label: mitochondrial matrix
  supported_by:
  - reference_id: PMID:17189267
    supporting_text: Mitochondrial heat shock protein 70 (mthsp70) functions as a
      mitochondrial import motor and is essential in mitochondrial biogenesis and
      energy generation in eukaryotic cells. HSP-6 (hsp70F) is a nematode orthologue
      of mthsp70.
  - reference_id: PMID:17189267
    supporting_text: Knockdown of HSP-6 by RNA interference in young adult nematodes
      caused a reduction in the levels of ATP-2, HSP-60 and CLK-1, leading to abnormal
      mitochondrial morphology and lower ATP levels.
- description: hsp-6 is the canonical marker gene for UPR-mt activation in C. elegans.
    The foundational study (PMID:15280428) demonstrated compartment-specific induction
    of hsp-6 by mitochondrial proteotoxic stress but not by heat shock or ER stress.
    hsp-6p::GFP is the standard reporter for UPR-mt studies, with induction being
    ATFS-1 dependent.
  molecular_function:
    id: GO:0016887
    label: ATP hydrolysis activity
  directly_involved_in:
  - id: GO:0034514
    label: mitochondrial unfolded protein response
  locations:
  - id: GO:0005759
    label: mitochondrial matrix
  supported_by:
  - reference_id: PMID:15280428
    supporting_text: hsp-6 and hsp-60 induction was specific to perturbed mitochondrial
      protein handling, as neither heat-shock nor endoplasmic reticulum stress nor
      manipulations that impair mitochondrial steps in intermediary metabolism or
      ATP synthesis activated the mitochondrial chaperone genes.
proposed_new_terms: []
suggested_questions:
- question: What specific co-chaperones (DNJ proteins) work with HSP-6 in C. elegans
    mitochondria?
  experts:
  - Mitochondrial proteostasis researchers
  - C. elegans geneticists
- question: Is HSP-6 involved in the folding of specific mitochondrial protein substrates,
    or is its substrate specificity broad?
  experts:
  - HSP70 chaperone biochemists
  - Mitochondrial protein import researchers
- question: What is the relative contribution of HSP-6 to import motor function versus
    post-import folding assistance?
  experts:
  - Mitochondrial protein import specialists
  - TIM23 complex researchers
suggested_experiments:
- description: Immunofluorescence or GFP-tagging to confirm mitochondrial matrix localization
    specifically (vs. outer membrane or intermembrane space)
  experiment_type: Subcellular localization
  hypothesis: HSP-6 localizes specifically to the mitochondrial matrix compartment
- description: Co-immunoprecipitation to identify specific protein interaction partners
    and substrates
  experiment_type: Protein interaction analysis
  hypothesis: HSP-6 interacts with TIM23 complex components and specific mitochondrial
    substrate proteins
- description: Genetic epistasis experiments with TIM23 complex components to confirm
    import motor function
  experiment_type: Genetic epistasis
  hypothesis: HSP-6 functions downstream of TIM23 in the protein import pathway
tags:
- caeel-upr-stress