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Exported on March 22, 2026 at 12:25 AM

Organism: Schizosaccharomyces pombe

Sequence:

MSMFGIGKNNQTINPQNIAMAEQEVEMMSDIFNRLVMTCHKKCISPKYYEADLTKGESVCIDRCVSKYFEANQSLSQHMQKRGQENPTP

Thinking Trace

I begin with the InterPro architecture. The polypeptide carries IPR035427 (Tim10-like domain superfamily, residues 15–88) and, nested within it, IPR004217 (Tim10-like domain, residues 18–81). This compact, overlapping arrangement defines the canonical small Tim chaperone fold: a helical hairpin core that oligomerizes into ring-shaped assemblies. This fold lacks catalytic motifs and instead creates a hydrophobic binding surface that stabilizes client segments. The Tim10-like architecture therefore dictates a non-enzymatic, multivalent binding role—precisely the design required for transient capture and handover of membrane-protein precursors.

From this domain logic, the primary molecular function resolves to protein binding (GO:0005515). The Tim10-like scaffold causes avid, surface-mediated interactions with nascent transmembrane clients and with other assembly factors rather than driving ATP-dependent remodeling. Such binding is directed toward preventing premature aggregation in the aqueous compartment and steering clients toward their assembly pathway.

This binding-driven mechanism naturally feeds into mitochondrial membrane protein biogenesis. Small Tim rings operate as intramitochondrial chaperones that shepherd hydrophobic precursors between import sites and assembly machines. That causal chain—hydrophobic client capture, safe transit, and assembly—places the protein squarely in mitochondrial organization and specifically in the pathway that builds inner-membrane complexes. Thus, at the biological process level, it contributes to mitochondrial organization (GO:0007005), by ensuring orderly assembly and maintenance of inner-membrane machinery.

The cellular context follows from the fold and pathway. Tim10-like modules are soluble within the mitochondrial interior and concentrate at the inner membrane face where assembly occurs. The absence of transmembrane segments and the chaperone fold argue for a soluble matrix/intermembrane-space role anchored near the inner membrane. Consequently, the cellular component is mitochondrial (GO:0005737), with a mechanistic locus at or near the inner membrane surface that receives hydrophobic clients.

Mechanistically, I hypothesize that this protein forms a small Tim oligomer that binds labile hydrophobic segments of inner-membrane complexes, then transfers them to assembly platforms. Likely interaction partners include other small Tim subunits that build the oligomeric ring; outer-membrane import assemblies that deliver precursors; and inner-membrane assembly modules that receive them. Together, these transient interactions create a relay that protects and positions client proteins for efficient inner-membrane biogenesis in fission yeast mitochondria.

Functional Summary

A mitochondrial intramitochondrial chaperone that assembles into small oligomeric rings to bind and shield hydrophobic segments of precursor membrane proteins. By transiently capturing clients and handing them off between import and assembly pathways, it promotes orderly biogenesis of inner-membrane complexes and thereby supports overall mitochondrial organization. Its soluble, non-enzymatic architecture positions it within the mitochondrial interior adjacent to the inner membrane, where it coordinates stepwise assembly events through multivalent protein binding.

UniProt Summary

Probable mitochondrial intermembrane chaperone that participates in the import and/or assembly of inner membrane proteins.

InterPro Domains

• Tim10-like domain superfamily (IPR035427, homologous_superfamily) — residues 15-88
• Tim10-like (IPR004217, domain) — residues 18-81

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), protein binding (GO:0005515)

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), localization (GO:0051179), establishment of localization (GO:0051234), cellular component organization or biogenesis (GO:0071840), cellular component organization (GO:0016043), transport (GO:0006810), organelle organization (GO:0006996), monoatomic ion transport (GO:0006811), mitochondrial organization (GO:0007005), monoatomic cation transport (GO:0006812), metal ion transport (GO:0030001), transition metal ion transport (GO:0000041), copper ion transport (GO:0006825)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), intracellular anatomical structure (GO:0005622), organelle (GO:0043226), mitochondrion (GO:0005737), intracellular organelle (GO:0043229), mitochondrion (GO:0005739), membrane-bounded organelle (GO:0043227), intracellular membrane-bounded organelle (GO:0043231)

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BioReason Chat Export

Exported on March 22, 2026 at 12:25 AM

Organism: Schizosaccharomyces pombe

Sequence:

MSMFGIGKNNQTINPQNIAMAEQEVEMMSDIFNRLVMTCHKKCISPKYYEADLTKGESVCIDRCVSKYFEANQSLSQHMQKRGQENPTP

Thinking Trace

I begin with the InterPro architecture. The polypeptide carries IPR035427 (Tim10-like domain superfamily, residues 15–88) and, nested within it, IPR004217 (Tim10-like domain, residues 18–81). This compact, overlapping arrangement defines the canonical small Tim chaperone fold: a helical hairpin core that oligomerizes into ring-shaped assemblies. This fold lacks catalytic motifs and instead creates a hydrophobic binding surface that stabilizes client segments. The Tim10-like architecture therefore dictates a non-enzymatic, multivalent binding role—precisely the design required for transient capture and handover of membrane-protein precursors.

From this domain logic, the primary molecular function resolves to protein binding (GO:0005515). The Tim10-like scaffold causes avid, surface-mediated interactions with nascent transmembrane clients and with other assembly factors rather than driving ATP-dependent remodeling. Such binding is directed toward preventing premature aggregation in the aqueous compartment and steering clients toward their assembly pathway.

This binding-driven mechanism naturally feeds into mitochondrial membrane protein biogenesis. Small Tim rings operate as intramitochondrial chaperones that shepherd hydrophobic precursors between import sites and assembly machines. That causal chain—hydrophobic client capture, safe transit, and assembly—places the protein squarely in mitochondrial organization and specifically in the pathway that builds inner-membrane complexes. Thus, at the biological process level, it contributes to mitochondrial organization (GO:0007005), by ensuring orderly assembly and maintenance of inner-membrane machinery.

The cellular context follows from the fold and pathway. Tim10-like modules are soluble within the mitochondrial interior and concentrate at the inner membrane face where assembly occurs. The absence of transmembrane segments and the chaperone fold argue for a soluble matrix/intermembrane-space role anchored near the inner membrane. Consequently, the cellular component is mitochondrial (GO:0005737), with a mechanistic locus at or near the inner membrane surface that receives hydrophobic clients.

Mechanistically, I hypothesize that this protein forms a small Tim oligomer that binds labile hydrophobic segments of inner-membrane complexes, then transfers them to assembly platforms. Likely interaction partners include other small Tim subunits that build the oligomeric ring; outer-membrane import assemblies that deliver precursors; and inner-membrane assembly modules that receive them. Together, these transient interactions create a relay that protects and positions client proteins for efficient inner-membrane biogenesis in fission yeast mitochondria.

Functional Summary

A mitochondrial intramitochondrial chaperone that assembles into small oligomeric rings to bind and shield hydrophobic segments of precursor membrane proteins. By transiently capturing clients and handing them off between import and assembly pathways, it promotes orderly biogenesis of inner-membrane complexes and thereby supports overall mitochondrial organization. Its soluble, non-enzymatic architecture positions it within the mitochondrial interior adjacent to the inner membrane, where it coordinates stepwise assembly events through multivalent protein binding.

UniProt Summary

Probable mitochondrial intermembrane chaperone that participates in the import and/or assembly of inner membrane proteins.

InterPro Domains

• Tim10-like domain superfamily (IPR035427, homologous_superfamily) — residues 15-88
• Tim10-like (IPR004217, domain) — residues 18-81

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), protein binding (GO:0005515)

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), localization (GO:0051179), establishment of localization (GO:0051234), cellular component organization or biogenesis (GO:0071840), cellular component organization (GO:0016043), transport (GO:0006810), organelle organization (GO:0006996), monoatomic ion transport (GO:0006811), mitochondrial organization (GO:0007005), monoatomic cation transport (GO:0006812), metal ion transport (GO:0030001), transition metal ion transport (GO:0000041), copper ion transport (GO:0006825)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), intracellular anatomical structure (GO:0005622), organelle (GO:0043226), mitochondrion (GO:0005737), intracellular organelle (GO:0043229), mitochondrion (GO:0005739), membrane-bounded organelle (GO:0043227), intracellular membrane-bounded organelle (GO:0043231)

Generated by BioReason

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model: Edison Scientific Literature
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organism: SCHPO
gene_id: Tim10
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protein_description: 'RecName: Full=Mitochondrial import inner membrane translocase
subunit tim10;'
gene_info: Name=tim10; ORFNames=SPAC222.03c;
organism_full: Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast).
protein_family: Belongs to the small Tim family. .
protein_domains: Tim10-like. (IPR004217); Tim10-like_dom_sf. (IPR035427); zf-Tim10_DDP
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Question

Gene Research for Functional Annotation

⚠️ 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: Q9UTE9
• Protein Description: RecName: Full=Mitochondrial import inner membrane translocase subunit tim10;
• Gene Information: Name=tim10; ORFNames=SPAC222.03c;
• Organism (full): Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast).
• Protein Family: Belongs to the small Tim family. .
• Key Domains: Tim10-like. (IPR004217); Tim10-like_dom_sf. (IPR035427); zf-Tim10_DDP (PF02953)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "tim10" matches the protein description above
2. Verify the organism is correct: Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast).
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 'tim10' 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 tim10 (gene ID: Tim10, UniProt: Q9UTE9) in SCHPO.

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

⚠️ 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: Q9UTE9
• Protein Description: RecName: Full=Mitochondrial import inner membrane translocase subunit tim10;
• Gene Information: Name=tim10; ORFNames=SPAC222.03c;
• Organism (full): Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast).
• Protein Family: Belongs to the small Tim family. .
• Key Domains: Tim10-like. (IPR004217); Tim10-like_dom_sf. (IPR035427); zf-Tim10_DDP (PF02953)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "tim10" matches the protein description above
2. Verify the organism is correct: Schizosaccharomyces pombe (strain 972 / ATCC 24843) (Fission yeast).
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 'tim10' 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 tim10 (gene ID: Tim10, UniProt: Q9UTE9) in SCHPO.

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.

Plan
- Objective 1: Verify identity and nomenclature for Schizosaccharomyces pombe tim10 (UniProt Q9UTE9) and confirm family/domain context. Completed: tim10 (ORF SPAC222.03c) encodes a small Tim family protein (Tim10-like domain; PF02953), annotated as a mitochondrial import inner membrane translocase subunit Tim10 in S. pombe (species context per prompt), consistent with small Tim proteins that function in the mitochondrial intermembrane space (IMS) as chaperones for the TIM22 pathway (no conflicting nomenclature found). (elder2023structurefunctionand pages 168-172)
- Objective 2: Gather 2023–2024 literature on small Tim proteins/TIM22 and any S. pombe–specific data. Completed: 2023 peer‑reviewed EMBO Reports paper on human small TIMs (Anderson et al. 2023), a 2023 thesis synthesizing primary literature on small Tims/TIM22 (Elder 2023), and a 2023 bioRxiv preprint on small Tims in T. brucei (Guillén et al. 2023). No S. pombe–specific primary studies surfaced; inference relies on conserved small Tim biology. (anderson2023humantim8atim8b pages 1-2, elder2023structurefunctionand pages 168-172, guillen2023uniqueinteractionsand pages 1-5, guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 11-15)
- Objective 3: Extract citable evidence on function, localization, complex membership, structure, and client spectrum; include URLs/dates. Completed below with citations. (petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2, anderson2023humantim8atim8b pages 1-2, elder2023structurefunctionand pages 168-172, guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 1-5, guillen2023uniqueinteractionsand pages 11-15)
- Objective 4: Synthesize a comprehensive report emphasizing 2023–2024 developments, applications, expert opinions, and relevant statistics. Completed below. (anderson2023humantim8atim8b pages 1-2, elder2023structurefunctionand pages 168-172, guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 1-5)
- Objective 5: Submit final, fully cited answer. Completed.

Comprehensive research report: tim10 (UniProt Q9UTE9) in Schizosaccharomyces pombe

1) Key concepts and definitions with current understanding
- Identity and family: tim10 (SPAC222.03c) in S. pombe encodes a small Tim family protein with a Tim10-like domain (pfam PF02953), characteristic of soluble IMS chaperones that assist hydrophobic precursors to the TIM22 translocase of the inner mitochondrial membrane (IMM) (UniProt description consistent with the small Tim family). As a small Tim, Tim10 typically partners with Tim9 to form a heterohexameric Tim9–Tim10 complex that acts in the IMS. While direct S. pombe studies were not retrieved, these features are deeply conserved across fungi and metazoans. Elder (2023) synthesizes the small Tim field and TIM22 pathway, providing primary citations to structural and mechanistic work on Tim9–Tim10 complexes. URL: https://doi.org/10.5525/gla.thesis.83542 (Jan 2023). (elder2023structurefunctionand pages 168-172)
- Localization: Small Tims (including Tim9/Tim10) are soluble IMS proteins. They chaperone hydrophobic segments of multi‑pass mitochondrial proteins between the TOM complex in the outer membrane and the TIM22 translocase in the IMM. The IMS localization and chaperone role are supported by multiple primary sources reviewed in Elder (2023) and by 2023 EMBO Reports work on human small TIMs. URL: https://doi.org/10.5525/gla.thesis.83542 (Jan 2023); https://doi.org/10.15252/embr.202256430 (Published online Jun 5, 2023). (elder2023structurefunctionand pages 168-172, anderson2023humantim8atim8b pages 1-2)
- Molecular function: The Tim9–Tim10 hexameric chaperone binds and stabilizes hydrophobic precursors (e.g., mitochondrial carrier family, SLC25) in the IMS, delivers them to the TIM22 translocase, often docking via Tim12, and facilitates their insertion into the IMM. Early biochemical reconstitution showed TOM plus Tim9/Tim10 complexes suffice to support translocation of ADP/ATP carrier-type substrates, highlighting the core chaperone function. URLs: Elder 2023 thesis (compiles Vasiljev et al. 2004 Mol Biol Cell https://doi.org/10.1091/mbc.E03-05-0272). (elder2023structurefunctionand pages 168-172)
- Complex membership and stoichiometry: In yeast, the soluble small Tim complexes in the IMS form heterohexamers: Tim9–Tim10 (3:3) and Tim8–Tim13 (3:3); Tim12 associates at the membrane with TIM22. Tim9 and Tim10 are essential for viability in S. cerevisiae and function as the major carrier chaperone; Tim12 is bound to the TIM22 complex. Although not shown directly for S. pombe here, the complex architecture is considered conserved. URL: https://doi.org/10.1002/iub.235 (Sep 2009). (petrakis2009mitochondrialatp‐independentchaperones pages 1-2, petrakis2009mitochondrialatp‐independentchaperones pages 2-4)
- Structural/biophysical features and domains: Small Tim subunits share a conserved twin Cys motif (twin CX3C), forming two intramolecular disulfide bonds that stabilize the fold in the IMS. The hexamer adopts a ring-like six-bladed alpha-propeller with “tentacle” helices thought to engage clients. Earlier work proposed Zn2+-binding by the CX3C motifs could contribute to folding in specific contexts (e.g., human Tim8/DDP1). URLs: https://doi.org/10.1002/iub.235 (Sep 2009). (petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)

2) Recent developments and latest research (prioritize 2023–2024)
- Human small TIMs and broader roles: Anderson et al. (2023) demonstrated that human Tim8a, Tim8b, and Tim13 not only act as small TIM chaperones in the IMS but also serve as auxiliary assembly factors for Complex IV, expanding the functional repertoire of small TIMs beyond carrier import. This underscores the functional adaptability of small TIM family members across eukaryotes. URL: https://doi.org/10.15252/embr.202256430 (Published online Jun 5, 2023). (anderson2023humantim8atim8b pages 1-2)
- Updated mechanistic synthesis: Elder (2023) provides an integrative 2023 synthesis of structural and biochemical literature on small Tims and the TIM22 pathway, including high-resolution structural insights into the Tim9•Tim10 complex and functional reconstitution of carrier import, which together underpin current models for small Tim–mediated chaperoning and TIM22 insertion. URL: https://doi.org/10.5525/gla.thesis.83542 (Jan 2023). (elder2023structurefunctionand pages 168-172)
- Comparative systems emphasize small Tim complexity: Guillén et al. (2023 preprint) reported organism-specific variations in trypanosomes where multiple small Tim complexes interface with a divergent TIM complex (TbTIM17), illustrating modularity of small Tim assemblies and their docking to IMM translocases. Although this is a non-fungal system and a preprint, it highlights conserved principles of IMS chaperone–translocase cooperation relevant to inference in S. pombe. URL: https://doi.org/10.1101/2023.05.29.542777 (posted May 31, 2023). (guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 1-5, guillen2023uniqueinteractionsand pages 11-15)

3) Current applications and real‑world implementations
- Disease relevance and clinical genetics: The small Tim family is implicated in human mitochondrial disease. Mutations in TIMM8A (human Tim8a/DDP1) cause Mohr‑Tranebjærg (deafness–dystonia) syndrome, demonstrating that perturbations in small TIM biology lead to neuromuscular/neurodegenerative phenotypes. While not directly S. pombe–related, this human genetic evidence underscores the essential role of small TIM chaperones in maintaining mitochondrial proteostasis, a conserved cellular requirement shared with fungi. URL: https://doi.org/10.1002/iub.235 (Sep 2009); https://doi.org/10.15252/embr.202256430 (Jun 2023). (petrakis2009mitochondrialatp‐independentchaperones pages 1-2, anderson2023humantim8atim8b pages 1-2)
- TIM22‑associated disease factors: The identification of AGK as a subunit of the human TIM22 complex links TIM22 dysfunction to Sengers syndrome; this helps contextualize how defects in the carrier import pathway manifest clinically and supports the importance of Tim9–Tim10 chaperoning upstream of TIM22. Elder (2023) cites Vukotic et al. (2017 Mol Cell) identifying AGK within the human TIM22 complex, connecting TIM22 pathway to disease. URL: https://doi.org/10.5525/gla.thesis.83542 (Jan 2023). (elder2023structurefunctionand pages 168-172)

4) Expert opinions and analysis from authoritative sources
- Consensus role of small Tims as IMS chaperones: Authoritative syntheses concur that Tim9–Tim10 hexamers are core IMS chaperones for hydrophobic precursors destined for TIM22, stabilizing clients post‑TOM and guiding to the IMM for insertion. Anderson et al. (2023) reiterate IMS localization and chaperone functions of small TIMs in humans; Elder (2023) compiles structural and biochemical evidence; Petrakis et al. (2009) discuss ATP‑independent chaperoning, essentiality of Tim9/Tim10 in yeast, and Tim12’s docking role at TIM22. URLs: https://doi.org/10.15252/embr.202256430 (Jun 2023); https://doi.org/10.5525/gla.thesis.83542 (Jan 2023); https://doi.org/10.1002/iub.235 (Sep 2009). (anderson2023humantim8atim8b pages 1-2, elder2023structurefunctionand pages 168-172, petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)
- Structural basis and domain logic: The conserved twin CX3C motif and the hexameric ring with tentacle helices provide a structural rationale for broad but selective binding to hydrophobic segments of clients, consistent with ATP‑independent chaperoning in the IMS redox environment. Petrakis et al. (2009) summarize these structural features and their functional implications. URL: https://doi.org/10.1002/iub.235 (Sep 2009). (petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)

5) Relevant statistics and data from recent studies
- Chaperone complex size and composition: Small Tim chaperones exist as ~70 kDa heterohexamers (e.g., Tim9–Tim10 3:3, Tim8–Tim13 3:3); human cells encode six small TIMs (Tim8a, Tim8b, Tim9, Tim10a, Tim10b, Tim13), which assemble into analogous hexamers that deliver membrane proteins to TIM22. Anderson et al. (2023) and prior literature summarized in Petrakis (2009) and Elder (2023) report these values. URLs: https://doi.org/10.15252/embr.202256430 (Jun 2023); https://doi.org/10.1002/iub.235 (Sep 2009); https://doi.org/10.5525/gla.thesis.83542 (Jan 2023). (anderson2023humantim8atim8b pages 1-2, petrakis2009mitochondrialatp‐independentchaperones pages 1-2, petrakis2009mitochondrialatp‐independentchaperones pages 2-4, elder2023structurefunctionand pages 168-172)
- Essentiality in fungi: Tim9 and Tim10 are essential for viability in S. cerevisiae, and a fraction of Tim9/Tim10 associates with the IMM‑bound TIM22 complex while Tim12 is exclusively associated with TIM22, delineating functional partitioning. This provides a strong basis for expecting essential or critical roles in S. pombe. URL: https://doi.org/10.1002/iub.235 (Sep 2009). (petrakis2009mitochondrialatp‐independentchaperones pages 1-2)

Organism‑specific note and verification of ambiguity
- We verified that the target is S. pombe tim10 (UniProt Q9UTE9; SPAC222.03c), a small Tim family protein with a Tim10‑like domain. Our literature scan did not identify S. pombe‑specific experimental papers on tim10; thus, specific phenotypes in S. pombe are inferred from conserved small Tim biology established in fungi and metazoans. We avoided conflating with similarly named genes in other organisms. URL: Elder 2023 (for conserved small Tim biology) https://doi.org/10.5525/gla.thesis.83542 (Jan 2023). (elder2023structurefunctionand pages 168-172)

Detailed functional model for S. pombe Tim10 (inferred from conserved evidence)
- Primary function: Tim10 forms a heterohexamer with Tim9 in the IMS to chaperone hydrophobic precursors, especially SLC25 carrier proteins, from TOM to the TIM22 complex; docking may involve a Tim12‑like subunit at TIM22. This model is supported by reconstitution of carrier translocation with TOM plus Tim9/Tim10 and by extensive structural studies of the Tim9•Tim10 complex. URL: Elder 2023 (compiling Vasiljev 2004 Mol Biol Cell https://doi.org/10.1091/mbc.E03-05-0272; Webb 2006 Mol Cell https://doi.org/10.1016/j.molcel.2005.11.010; Weinhäupl 2018 Cell https://doi.org/10.1016/j.cell.2018.10.039). (elder2023structurefunctionand pages 168-172)
- Substrates: The principal client spectrum includes mitochondrial carrier family proteins (e.g., ADP/ATP carrier) and other multi‑spanning IMM proteins. Different small Tim assemblies (Tim9–Tim10 vs Tim8–Tim13) have overlapping but distinct substrate specificities, with Tim9–Tim10 favoring carrier proteins. URLs: Elder 2023 (Jan 2023); Petrakis 2009 (Sep 2009). (elder2023structurefunctionand pages 168-172, petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)
- Localization: IMS, where the oxidizing milieu supports twin CX3C disulfide formation and ATP‑independent client binding and release. URL: Petrakis 2009 (Sep 2009); Anderson 2023 (Jun 2023). (petrakis2009mitochondrialatp‐independentchaperones pages 2-4, anderson2023humantim8atim8b pages 1-2, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)
- Pathway context: TIM22 carrier translocase in the IMM receives the small Tim–bound clients and inserts them laterally. Small Tim complexes also transiently associate with the TIM22 machinery, mediated by a membrane‑proximal small Tim (Tim12 in budding yeast). URLs: Elder 2023 (Jan 2023); Petrakis 2009 (Sep 2009). (elder2023structurefunctionand pages 168-172, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)

Limitations and open questions
- Species‑specific knowledge gap: Direct genetic, proteomic, or structural analyses of S. pombe tim10 were not located in this search, and most detailed mechanistic/structural insights derive from S. cerevisiae and metazoan systems. Nonetheless, the deep conservation of small Tim domain architecture, complex stoichiometry, IMS localization, and TIM22 pathway logic supports the assignments above for S. pombe Tim10. URL: Elder 2023 (Jan 2023). (elder2023structurefunctionand pages 168-172)

References with URLs and publication dates
- Anderson AJ et al., EMBO Reports. “Human Tim8a, Tim8b and Tim13 are auxiliary assembly factors of mature Complex IV.” Published online Jun 5, 2023. URL: https://doi.org/10.15252/embr.202256430. (anderson2023humantim8atim8b pages 1-2)
- Elder A. Thesis. “Structure, function and mitochondrial targeting of sideroflexin-3 (SFXN3).” Jan 2023. URL: https://doi.org/10.5525/gla.thesis.83542. Sections cited compile primary literature on small Tims/TIM22. (elder2023structurefunctionand pages 168-172)
- Petrakis N, Alcock F, Tokatlidis K. IUBMB Life. “Mitochondrial ATP-independent chaperones.” Sep 2009. URL: https://doi.org/10.1002/iub.235. (petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2)
- Guillén LSQ et al. bioRxiv preprint. “Unique interactions and functions of the mitochondrial small Tims in Trypanosoma brucei.” Posted May 31, 2023. URL: https://doi.org/10.1101/2023.05.29.542777. (guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 1-5, guillen2023uniqueinteractionsand pages 11-15)

Summary
- The S. pombe gene tim10 (Q9UTE9; SPAC222.03c) encodes a small Tim family protein localized to the mitochondrial IMS, forming a Tim9–Tim10 heterohexamer that functions as an ATP‑independent chaperone to deliver hydrophobic multi-pass precursors—especially mitochondrial carrier proteins—to the TIM22 translocase for insertion into the IMM, a model strongly supported by conserved evidence from fungi and metazoans. Structural hallmarks (twin CX3C motif/disulfides; Tim10-like domain) and essential roles (by analogy to yeast) underpin its core function in mitochondrial protein biogenesis. Recent 2023 work extends small TIM biology to additional roles (e.g., Complex IV assembly in human cells), highlighting the broader significance of this protein family in mitochondrial proteostasis. (anderson2023humantim8atim8b pages 1-2, elder2023structurefunctionand pages 168-172, petrakis2009mitochondrialatp‐independentchaperones pages 2-4, petrakis2009mitochondrialatp‐independentchaperones pages 1-2, guillen2023uniqueinteractionsand pages 28-32, guillen2023uniqueinteractionsand pages 1-5, guillen2023uniqueinteractionsand pages 11-15)

References

1. (elder2023structurefunctionand pages 168-172): Amy Elder. Structure, function and mitochondrial targeting of sideroflexin-3 (sfxn3). Text, Jan 2023. URL: https://doi.org/10.5525/gla.thesis.83542, doi:10.5525/gla.thesis.83542. This article has 0 citations and is from a peer-reviewed journal.

2. (anderson2023humantim8atim8b pages 1-2): Alexander J Anderson, Jordan J Crameri, Ching‐Seng Ang, Tess R Malcolm, Yilin Kang, Megan J Baker, Catherine S Palmer, Alice J Sharpe, Luke E Formosa, Katherine Ganio, Michael J Baker, Christopher A McDevitt, Michael T Ryan, Megan J Maher, and Diana Stojanovski. Human tim8a, tim8b and tim13 are auxiliary assembly factors of mature complex iv. EMBO reports, Jun 2023. URL: https://doi.org/10.15252/embr.202256430, doi:10.15252/embr.202256430. This article has 19 citations and is from a highest quality peer-reviewed journal.

3. (guillen2023uniqueinteractionsand pages 1-5): Linda S. Quiñones Guillén, Fidel Soto Gonzalez, Chauncey Darden, Muhammad Bismillah Khan, A. Tripathi, Joseph T. Smith, Ayorinde Cooley, Victor Paromov, Jamaine Davis, Smitā Miśra, and Minu Chaudhuri. Unique interactions and functions of the mitochondrial small tims in trypanosoma brucei. bioRxiv, May 2023. URL: https://doi.org/10.1101/2023.05.29.542777, doi:10.1101/2023.05.29.542777. This article has 2 citations and is from a poor quality or predatory journal.

4. (guillen2023uniqueinteractionsand pages 28-32): Linda S. Quiñones Guillén, Fidel Soto Gonzalez, Chauncey Darden, Muhammad Bismillah Khan, A. Tripathi, Joseph T. Smith, Ayorinde Cooley, Victor Paromov, Jamaine Davis, Smitā Miśra, and Minu Chaudhuri. Unique interactions and functions of the mitochondrial small tims in trypanosoma brucei. bioRxiv, May 2023. URL: https://doi.org/10.1101/2023.05.29.542777, doi:10.1101/2023.05.29.542777. This article has 2 citations and is from a poor quality or predatory journal.

5. (guillen2023uniqueinteractionsand pages 11-15): Linda S. Quiñones Guillén, Fidel Soto Gonzalez, Chauncey Darden, Muhammad Bismillah Khan, A. Tripathi, Joseph T. Smith, Ayorinde Cooley, Victor Paromov, Jamaine Davis, Smitā Miśra, and Minu Chaudhuri. Unique interactions and functions of the mitochondrial small tims in trypanosoma brucei. bioRxiv, May 2023. URL: https://doi.org/10.1101/2023.05.29.542777, doi:10.1101/2023.05.29.542777. This article has 2 citations and is from a poor quality or predatory journal.

6. (petrakis2009mitochondrialatp‐independentchaperones pages 2-4): Nikos Petrakis, Felicity Alcock, and Kostas Tokatlidis. Mitochondrial atp‐independent chaperones. IUBMB Life, 61:909-914, Sep 2009. URL: https://doi.org/10.1002/iub.235, doi:10.1002/iub.235. This article has 20 citations and is from a peer-reviewed journal.

7. (petrakis2009mitochondrialatp‐independentchaperones pages 1-2): Nikos Petrakis, Felicity Alcock, and Kostas Tokatlidis. Mitochondrial atp‐independent chaperones. IUBMB Life, 61:909-914, Sep 2009. URL: https://doi.org/10.1002/iub.235, doi:10.1002/iub.235. This article has 20 citations and is from a peer-reviewed journal.

Citations

1. elder2023structurefunctionand pages 168-172
2. guillen2023uniqueinteractionsand pages 1-5
3. guillen2023uniqueinteractionsand pages 28-32
4. guillen2023uniqueinteractionsand pages 11-15
5. https://doi.org/10.5525/gla.thesis.83542
6. https://doi.org/10.15252/embr.202256430
7. https://doi.org/10.1091/mbc.E03-05-0272
8. https://doi.org/10.1002/iub.235
9. https://doi.org/10.1101/2023.05.29.542777
10. https://doi.org/10.1091/mbc.E03-05-0272;
11. https://doi.org/10.1016/j.molcel.2005.11.010;
12. https://doi.org/10.1016/j.cell.2018.10.039
13. https://doi.org/10.15252/embr.202256430.
14. https://doi.org/10.5525/gla.thesis.83542.
15. https://doi.org/10.1002/iub.235.
16. https://doi.org/10.1101/2023.05.29.542777.
17. https://doi.org/10.5525/gla.thesis.83542,
18. https://doi.org/10.15252/embr.202256430,
19. https://doi.org/10.1101/2023.05.29.542777,
20. https://doi.org/10.1002/iub.235,

BioReason-Pro RL Review: Tim10 (S. pombe)

Source: Tim10-deep-research-bioreason-rl.md

• Correctness: 4/5
• Completeness: 4/5

Functional Summary Review

BioReason's functional summary is largely accurate:

A mitochondrial intramitochondrial chaperone that assembles into small oligomeric rings to bind and shield hydrophobic segments of precursor membrane proteins. By transiently capturing clients and handing them off between import and assembly pathways, it promotes orderly biogenesis of inner-membrane complexes and thereby supports overall mitochondrial organization.

This correctly captures Tim10's core function as a subunit of the heterohexameric Tim9-Tim10 chaperone complex in the mitochondrial intermembrane space. The curated review describes Tim10 forming a 3:3 heterohexamer with Tim9 that acts as an ATP-independent chaperone for hydrophobic carrier protein precursors in the TIM22 import pathway (PMID:16387659, PMID:14726512).

The key claims are well-supported:

assembles into small oligomeric rings to bind and shield hydrophobic segments of precursor membrane proteins

The curated review confirms the hexameric six-bladed alpha-propeller structure with "tentacle-like helices that engage hydrophobic client proteins" (PMID:16387659).

transiently capturing clients and handing them off between import and assembly pathways

This accurately describes the relay from TOM complex to TIM22 translocase.

Minor issues:
- BioReason says "mitochondrial" for cellular component but writes GO:0005737 (cytoplasm) in the GO terms section, which is an error (likely confusing mitochondrion GO:0005739 with cytoplasm). The curated review correctly places Tim10 in the mitochondrial intermembrane space (GO:0005758).
- BioReason describes it generically as "protein binding" for molecular function. The curated review identifies the more specific GO:0140309 (unfolded protein carrier activity) and proposes GO:0140318 (protein transporter activity) as a replacement for the membrane insertase annotation.
- BioReason does not mention the twin CX3C motif that forms disulfide bonds in the IMS, which is an important structural feature.
- BioReason does not mention the specific substrate class (mitochondrial carrier family/SLC25 proteins).

Comparison with interpro2go:

There are no interpro2go (GO_REF:0000002) annotations for Tim10 in the curated review. The domain annotations (Tim10-like domain superfamily IPR035427, Tim10-like domain IPR004217) correctly define the protein family. BioReason accurately extends these domain annotations into a functional narrative that matches the curated biology. The IBA annotations (GO_REF:0000033) provide the functional context that BioReason largely recapitulates. BioReason provides a reasonable synthesis of the domain architecture into function, though it could be more specific about the TIM22 pathway and carrier protein substrates.

Notes on thinking trace

The trace correctly identifies the Tim10-like fold and its non-enzymatic chaperone function. The mechanistic hypothesis about oligomeric ring formation and hydrophobic client binding is well-supported. The interaction partner predictions (other small Tim subunits, outer membrane import assemblies, inner membrane assembly modules) are reasonable.