atg1

UniProt ID: Q86CS2
Organism: Dictyostelium discoideum
Review Status: COMPLETE
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Gene Description

atg1 encodes the Dictyostelium discoideum ortholog of the Atg1/ULK1 serine/threonine protein kinase, the most upstream component of the macroautophagy induction machinery. The protein has an N-terminal protein kinase domain (residues ~7-266) followed by an asparagine/glutamine-rich low-complexity region and a conserved C-terminal domain required for its localization to forming autophagosomes. Atg1 is the catalytic subunit of the Atg1 kinase complex (with Atg13 and Atg101), and its kinase activity initiates phagophore/autophagosome formation. Because Dictyostelium undergoes starvation-induced multicellular development that depends on autophagy for nutrient mobilization, Atg1 is essential for aggregation and for normal fruiting-body (sorocarp) formation, and it is required for the vacuolar (autophagic) cell death of terminally differentiating cells. Atg1-dependent autophagy also contributes to cell-autonomous defense against ingested bacteria and yeasts and to nutrient and energy homeostasis, and the kinase additionally influences macropinocytosis, cell size and nuclear division, gene expression, and mitochondrial energy balance. Atg1 localizes predominantly to the cytoplasm and cytosol, with a pool at the preautophagosomal structure (phagophore assembly site) membrane.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005737 cytoplasm
IBA
GO_REF:0000033
ACCEPT
Summary: Cytoplasmic localization is correct and directly supported by experimental evidence in Dictyostelium; Atg1-GFP shows a general cytoplasmic distribution.
Reason: Atg1 acts predominantly in the cytoplasm, consistent with direct localization data and with its role as the cytoplasmic autophagy-initiating kinase.
Supporting Evidence:
PMID:26246495
Atg1 fused to GFP has been shown previously to have a general cytoplasmic pattern in Dictyostelium cells with no specific puncta localization
GO:0000045 autophagosome assembly
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1 is the upstream kinase that initiates autophagosome formation, a core conserved function directly demonstrated in Dictyostelium.
Reason: Kinase-dead Atg1 blocks functional autophagosome formation and Atg1 is required for macroautophagy, making autophagosome assembly a core function.
Supporting Evidence:
PMID:17031001
In cells expressing dominant-negative DdAtg1, autophagosomes are formed and accumulate but seem not to be functional
GO:0000423 mitophagy
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: Mitophagy is a conserved ULK1/Atg1 selective-autophagy function, but direct evidence in Dictyostelium is lacking; the one study of Atg1 and mitochondria concluded an ancillary role in energy balance rather than direct organelle turnover.
Reason: The IBA transfer of mitophagy from ULK1 orthologs is plausible but not demonstrated for Dictyostelium Atg1, where mitochondrial effects appear indirect; retained as non-core pending direct evidence.
Supporting Evidence:
PMID:39056773
Atg1's effects on energy homeostasis indicate a peripheral ancillary role in the mitochondrial signalling network, with effects on energy balance rather than direct effects on electron transport chain function
GO:0010506 regulation of autophagy
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1 is the induction-regulating kinase of the autophagy pathway, a core conserved function.
Reason: As the catalytic subunit of the Atg1 complex, Atg1 controls the induction of autophagy, consistent with this annotation.
Supporting Evidence:
PMID:26246495
The first steps of induction and nucleation are controlled by the serine/threonine kinase Atg1/ULK1 and the class III PI3 K VPS34
GO:0042594 response to starvation
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1-dependent autophagy is induced by and required for survival during starvation, well supported in Dictyostelium.
Reason: atg1 mutants show reduced survival during nitrogen starvation, directly linking Atg1 to the starvation response.
Supporting Evidence:
PMID:14736886
reduced survival during nitrogen starvation
GO:0061709 reticulophagy
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: Reticulophagy (ER-phagy) is a conserved selective-autophagy branch inferred from orthologs, but has not been demonstrated for Dictyostelium Atg1.
Reason: No direct evidence for ER-selective autophagy by Dictyostelium Atg1; retained as a non-core phylogenetic inference.
GO:0000407 phagophore assembly site
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1 acts at the phagophore assembly site (preautophagosomal structure), where it initiates autophagosome formation.
Reason: Kinase-dead Atg1 colocalizes with the Atg8 marker of preautophagosomal structures, supporting activity at this site.
Supporting Evidence:
PMID:17031001
colocalizes with red fluorescent protein (RFP)-tagged DdAtg8, a marker of
GO:0005776 autophagosome
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1 localizes to preautophagosomal structures and autophagosomes as shown by colocalization with the Atg8 marker.
Reason: Direct colocalization of Atg1 with RFP-Atg8-labeled autophagosomes supports this localization annotation.
Supporting Evidence:
PMID:17031001
a marker of preautophagosomal structures and autophagosomes
GO:0004674 protein serine/threonine kinase activity
IBA
GO_REF:0000033
ACCEPT
Summary: Atg1 is a serine/threonine protein kinase; this is the core molecular function.
Reason: The conserved kinase domain and demonstrated kinase-dependent (dominant-negative kinase-dead) function establish Ser/Thr kinase activity as the core molecular function.
Supporting Evidence:
PMID:17031001
Kinase-negative DdAtg1 acts in a
GO:0034045 phagophore assembly site membrane
IBA
GO_REF:0000033
MODIFY
Summary: Atg1 is a constituent of the phagophore assembly site, which is a protein condensate rather than a membrane-bounded structure.
Reason: The Atg1 complex is the phagophore assembly site, not a resident of a membrane bounding it: in S. cerevisiae the PAS is a liquid-like condensate of the Atg1 complex, tethered to the vacuolar membrane by protein-protein interactions rather than delimited by a bilayer (PMID:32025038). GO:0034045 asserts a bounding membrane the PAS does not have (GO issue #29437), and the cited UniProt location SL-0221 is the propagation source rather than independent evidence. Generalize to the assembly site itself. The supporting observation - Atg1 as a marker of preautophagosomal structures - is unchanged and supports GO:0000407 directly.
Propagation Review
Root cause: TERM SCOPING PROBLEM
Failure modes: GRANULARITY MISMATCH
Sources checked:
PANTHER:PTN000681273 Β· Atg1/ULK ancestral node SUPPORTS TRANSFER
The node call is right about where Atg1 acts; the defect is in the term, which propagates unchanged to every descendant.
UniProtKB:O75385 Β· ULK1 (human) SOURCE WEAK OR INFERRED
Seed carrying the same UniProt SL-0221-derived location, so the propagation adds no independent evidence for a PAS membrane.
Proposed replacements: phagophore assembly site
Supporting Evidence:
PMID:17031001
a marker of preautophagosomal structures and autophagosomes
GO:0005829 cytosol
IBA
GO_REF:0000033
ACCEPT
Summary: Consistent with the observed diffuse cytoplasmic/cytosolic distribution of Atg1.
Reason: Atg1-GFP shows a general cytoplasmic pattern, consistent with a cytosolic pool.
Supporting Evidence:
PMID:26246495
Atg1 fused to GFP has been shown previously to have a general cytoplasmic pattern in Dictyostelium cells with no specific puncta localization
GO:0034727 piecemeal microautophagy of the nucleus
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: A yeast-derived selective microautophagy process; not demonstrated for Dictyostelium Atg1.
Reason: No direct evidence in Dictyostelium; retained as a non-core phylogenetic inference from fungal orthologs.
GO:0004672 protein kinase activity
IEA
GO_REF:0000002
ACCEPT
Summary: General protein kinase activity, a correct parent term of the specific Ser/Thr kinase activity.
Reason: Correct but less specific than protein serine/threonine kinase activity; the more specific term is captured elsewhere.
Supporting Evidence:
PMID:17031001
these domains are essential for autophagy and development
GO:0004674 protein serine/threonine kinase activity
IEA
GO_REF:0000120
ACCEPT
Summary: Core molecular function, correctly assigned by automated methods.
Reason: Atg1 belongs to the APG1/unc-51/ULK1 Ser/Thr kinase subfamily; this is the core molecular function.
Supporting Evidence:
PMID:26246495
the serine/threonine kinase Atg1/ULK1
GO:0005524 ATP binding
IEA
GO_REF:0000002
ACCEPT
Summary: ATP binding is required for kinase catalysis and is supported by the conserved ATP-binding motif in the kinase domain.
Reason: The protein has a canonical protein kinase ATP-binding site; ATP binding is intrinsic to its catalytic function.
Supporting Evidence:
PMID:26246495
the serine/threonine kinase Atg1/ULK1
GO:0005737 cytoplasm
IEA
GO_REF:0000044
ACCEPT
Summary: Cytoplasmic localization from UniProt subcellular location mapping; correct.
Reason: Consistent with direct experimental evidence for cytoplasmic localization.
Supporting Evidence:
PMID:26246495
Atg1 fused to GFP has been shown previously to have a general cytoplasmic pattern in Dictyostelium cells with no specific puncta localization
GO:0034045 phagophore assembly site membrane
IEA
GO_REF:0000044
MODIFY
Summary: Preautophagosomal structure membrane localization propagated from the UniProt SL-0221 subcellular location; the assembly site is not membrane-bounded.
Reason: The Atg1 complex is the phagophore assembly site, not a resident of a membrane bounding it: in S. cerevisiae the PAS is a liquid-like condensate of the Atg1 complex, tethered to the vacuolar membrane by protein-protein interactions rather than delimited by a bilayer (PMID:32025038). GO:0034045 asserts a bounding membrane the PAS does not have (GO issue #29437), and the cited UniProt location SL-0221 is the propagation source rather than independent evidence. Generalize to the assembly site itself. The supporting observation - Atg1 as a marker of preautophagosomal structures - is unchanged and supports GO:0000407 directly.
Proposed replacements: phagophore assembly site
Supporting Evidence:
PMID:17031001
a marker of preautophagosomal structures and autophagosomes
GO:0106310 protein serine kinase activity
IEA
GO_REF:0000116
ACCEPT
Summary: Serine kinase activity assigned via Rhea reaction mapping; consistent with the Ser/Thr kinase activity of Atg1.
Reason: Correct reflection of the phosphotransferase reaction catalyzed by this Ser/Thr kinase.
Supporting Evidence:
PMID:26246495
the serine/threonine kinase Atg1/ULK1
GO:0071692 protein localization to extracellular region
IMP
PMID:38986731
Trafficking of adhesion and aggregation-modulating proteins ...
KEEP AS NON CORE
Summary: atg1 (with atg9) modulates the intracellular and extracellular amounts of the adhesion protein CadA and the secreted counting factor CtnA during aggregation, an autophagy-dependent secretion role.
Reason: The effect on extracellular protein levels is a downstream consequence of Atg1-dependent autophagy and unconventional secretion, not a core molecular function; retained as a non-core process.
Supporting Evidence:
PMID:38986731
The intracellular and extracellular amounts of CadA are modulated by autophagy genes
GO:0005737 cytoplasm
ISS
GO_REF:0000024
ACCEPT
Summary: Cytoplasmic localization inferred from orthologs; consistent with direct Dictyostelium data.
Reason: Supported by direct experimental localization of Atg1 to the cytoplasm.
Supporting Evidence:
PMID:26246495
Atg1 fused to GFP has been shown previously to have a general cytoplasmic pattern in Dictyostelium cells with no specific puncta localization
GO:0034045 phagophore assembly site membrane
ISS
GO_REF:0000024
MODIFY
Summary: PAS membrane localization inferred from orthologues; the ortholog annotations rest on the same UniProt location and inherit its error.
Reason: The Atg1 complex is the phagophore assembly site, not a resident of a membrane bounding it: in S. cerevisiae the PAS is a liquid-like condensate of the Atg1 complex, tethered to the vacuolar membrane by protein-protein interactions rather than delimited by a bilayer (PMID:32025038). GO:0034045 asserts a bounding membrane the PAS does not have (GO issue #29437), and the cited UniProt location SL-0221 is the propagation source rather than independent evidence. Generalize to the assembly site itself. The supporting observation - Atg1 as a marker of preautophagosomal structures - is unchanged and supports GO:0000407 directly.
Proposed replacements: phagophore assembly site
Supporting Evidence:
PMID:17031001
a marker of preautophagosomal structures and autophagosomes
GO:0106310 protein serine kinase activity
ISS
GO_REF:0000024
ACCEPT
Summary: Serine kinase activity inferred from sequence similarity; consistent with the core Ser/Thr kinase function.
Reason: Correct reflection of Atg1 kinase activity.
Supporting Evidence:
PMID:26246495
the serine/threonine kinase Atg1/ULK1
GO:0000902 cell morphogenesis
IMP
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: atg1 null cells are consistently smaller and show altered nuclear division; this reflects effects on cell size/division rather than a dedicated morphogenetic program.
Reason: The cell-size phenotype is a pleiotropic consequence of altered autophagy and growth/energy homeostasis, not a core function; retained as non-core.
Supporting Evidence:
PMID:39056773
the null mutant exhibited consistently smaller average cell sizes when grown axenically
GO:0009267 cellular response to starvation
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: Atg1 increases tolerance of Dictyostelium to starvation, consistent with its role in starvation-induced autophagy.
Reason: A genuine, experimentally supported role, but downstream of the core kinase/autophagy function; retained as non-core.
Supporting Evidence:
PMID:39056773
Atg1 increases the tolerance of D. discoideum to starvation and cAMP treatment
GO:0030587 sorocarp development
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: Altered atg1 expression produces smaller fruiting bodies and multi-tipped aggregates, confirming a role in multicellular (sorocarp) development.
Reason: A pleiotropic developmental role that follows from Atg1-dependent autophagy during starvation-induced development; retained as non-core.
Supporting Evidence:
PMID:39056773
both atg1 antisense inhibition and overexpression resulted in smaller fruiting bodies
GO:0048548 regulation of pinocytosis
IMP
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: Atg1 positively regulates macropinocytosis; the null mutant has a macropinocytic defect and uptake correlates with atg1 expression.
Reason: A real, experimentally supported regulatory effect on macropinocytic uptake, but a downstream/pleiotropic role rather than a core function.
Supporting Evidence:
PMID:39056773
the atg1 null mutant displayed a macropinocytic defect
GO:0010629 negative regulation of gene expression
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: Overexpression data suggest Atg1 negatively regulates the prestalk marker ecmA; the effect on individual genes was modest.
Reason: A downstream developmental gene-expression effect, supported but not a core molecular function; retained as non-core.
Supporting Evidence:
PMID:39056773
This suggests that Atg1 negatively regulates prestalk gene (ecmA) expression
GO:0009617 response to bacterium
IMP
PMID:22575510
Lipopolysaccharide induction of autophagy is associated with...
KEEP AS NON CORE
Summary: atg1 is required for LPS-enhanced clearance of phagocytosed bacteria, linking Atg1-dependent autophagy to the antibacterial response.
Reason: A genuine cell-autonomous defense role mediated by autophagy, but downstream of the core kinase/autophagy function; retained as non-core.
Supporting Evidence:
PMID:22575510
LPS pre-treatment did not enhance clearance of phagocytized S. aureus in cells deficient for either atg1 or atg9
GO:0031152 aggregation involved in sorocarp development
IMP
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: atg1-null cells are unable to aggregate, a hallmark of severe autophagy impairment in Dictyostelium development.
Reason: An experimentally established developmental phenotype downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:26246495
Amoebas in which Atg1 has been knocked out are unable to aggregate
GO:0043327 chemotaxis to cAMP
IMP
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
UNDECIDED
Summary: This study measured cAMP/starvation survival and aggregation timing but did not directly assay chemotaxis to cAMP; a direct chemotaxis role for Atg1 cannot be verified from the available text.
Reason: The cited paper does not present a direct chemotaxis assay, and antisense inhibition had no pronounced effect on aggregation; the supporting evidence for a specific chemotaxis-to-cAMP function cannot be verified.
GO:0043457 regulation of cellular respiration
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: Knockout of atg1 alters mitochondrial and non-mitochondrial respiration, supporting a role in modulating cellular respiration.
Reason: An experimentally supported but indirect/peripheral effect on energy homeostasis, not a core molecular function; retained as non-core.
Supporting Evidence:
PMID:39056773
knocking out atg1 caused reductions in basal mitochondrial and non-mitochondrial respiration
GO:0043653 mitochondrial fragmentation involved in apoptotic process
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
UNDECIDED
Summary: The cited study characterized mitochondrial membrane mass, potential, ROS and respiration but did not demonstrate mitochondrial fragmentation as part of an apoptotic process; Dictyostelium cell death is characteristically non-apoptotic.
Reason: The specific term (apoptotic mitochondrial fragmentation) is not supported by the available text and apoptosis is not an established Dictyostelium cell-death mode; the basis for this annotation cannot be verified.
GO:0044351 macropinocytosis
IDA
PMID:39056773
The Multifaceted Interactions of Dictyostelium Atg1 with Mit...
KEEP AS NON CORE
Summary: atg1-null cells display a macropinocytic defect and macropinocytic uptake correlates positively with atg1 expression.
Reason: A genuine effect on macropinocytosis, but a downstream/pleiotropic role rather than a core molecular function; retained as non-core.
Supporting Evidence:
PMID:39056773
macropinocytic uptake rates were positively correlated with the atg1 expression index
GO:0004672 protein kinase activity
IDA
PMID:17031001
Function of the Dictyostelium discoideum Atg1 kinase during ...
ACCEPT
Summary: Direct evidence that the Atg1 kinase domain is essential for function; kinase-dead Atg1 acts as a dominant negative.
Reason: The kinase domain is essential for autophagy and development, and a kinase-negative mutant is dominant-negative, directly demonstrating catalytic protein kinase function.
Supporting Evidence:
PMID:17031001
these domains are essential for autophagy and development
GO:0016236 macroautophagy
IMP
PMID:17031001
Function of the Dictyostelium discoideum Atg1 kinase during ...
ACCEPT
Summary: Atg1 kinase and its conserved C-terminal domain are essential for macroautophagy in Dictyostelium, a core function.
Reason: Kinase-dead Atg1 blocks functional autophagy and the domains are essential for autophagy; macroautophagy is a core biological process for Atg1.
Supporting Evidence:
PMID:17031001
In cells expressing dominant-negative DdAtg1, autophagosomes are formed and accumulate but seem not to be functional
GO:0048102 autophagic cell death
IMP
PMID:15358773
Autophagy gene disruption reveals a non-vacuolar cell death ...
KEEP AS NON CORE
Summary: atg1 disruption blocks autophagy and vacuolization in the developmental vacuolar cell death model, showing Atg1 is required for autophagic (vacuolar) cell death.
Reason: An experimentally supported developmental cell-death role that is downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:15358773
led in atg1 mutant cells to impaired autophagy and to no vacuolization
GO:0008047 enzyme activator activity
IDA
PMID:26246495
Dissecting the function of Atg1 complex in Dictyostelium aut...
KEEP AS NON CORE
Summary: Atg1 positively regulates the activity of the pentose-phosphate-pathway enzyme transketolase (TKT), with which it physically interacts; TKT activity rises with Atg1 overexpression and falls in atg1-null or kinase-dead conditions.
Reason: Atg1 acts as a positive regulator of TKT activity (likely via its kinase function), but this enzyme-activation role is a specialized regulatory link rather than the core evolved molecular function; retained as non-core.
Supporting Evidence:
PMID:26246495
There is an increase in activity in cells overexpressing Atg1. By contrast, TKT activity decreases in cells in which atg1 has been deleted
GO:0097300 programmed necrotic cell death
IDA
PMID:17150370
From autophagic to necrotic cell death in Dictyostelium.
UNDECIDED
Summary: This review describes that disrupting atg1 reveals a non-vacuolar (necrotic-like) cell death pathway; necrotic death occurs in the absence of Atg1 rather than requiring it, so a positive involvement of Atg1 in necrotic death is not clearly supported.
Reason: The relationship between Atg1 and necrotic cell death is indirect (necrosis is unmasked when autophagic death is blocked); the supporting text is from a review and does not establish that Atg1 is involved_in programmed necrotic death.
GO:0005515 protein binding
IPI
PMID:31680241
AMPKΞ± promotes basal autophagy induction in Dictyostelium di...
KEEP AS NON CORE
Summary: Co-immunoprecipitation shows an AMPK-ATG1 interaction conserved in basal autophagy. Bare 'protein binding' is uninformative; the meaningful content is the specific interaction with AMPK.
Reason: Per curation guidance, generic protein binding is not retained as a core function; the AMPK interaction is captured here as a non-core regulatory partnership.
Supporting Evidence:
PMID:31680241
Co-immunoprecipitation studies show conservation of the AMPK-ATG1
GO:0050830 defense response to Gram-positive bacterium
IDA
PMID:28414774
Mycobacterium marinum antagonistically induces an autophagic...
UNDECIDED
Summary: This study focuses on the ESX-1/TORC1-dependent manipulation of autophagy by Mycobacterium marinum; a specific, verifiable role for Atg1 in defense against a Gram-positive bacterium is not evident from the available text.
Reason: The cached text does not establish an Atg1-specific defense role against Gram-positive bacteria; the annotation cannot be verified from the available evidence.
GO:1905037 autophagosome organization
IMP
PMID:28414774
Mycobacterium marinum antagonistically induces an autophagic...
KEEP AS NON CORE
Summary: Atg1 is required for autophagosome formation/organization, an essentially core autophagy function; autophagosomes formed without functional Atg1 are aberrant.
Reason: Autophagosome organization is closely tied to Atg1's core autophagy-initiating role; captured here as a non-core process-level annotation with the core function recorded under macroautophagy/autophagosome assembly.
Supporting Evidence:
PMID:17031001
In cells expressing dominant-negative DdAtg1, autophagosomes are formed and accumulate but seem not to be functional
GO:0005515 protein binding
IPI
PMID:26246495
Dissecting the function of Atg1 complex in Dictyostelium aut...
KEEP AS NON CORE
Summary: Yeast two-hybrid and pull-down show Atg1 interacts with Atg13 and with the pentose-phosphate enzyme transketolase (TKT). Bare 'protein binding' is uninformative; the specific partners are the meaningful content.
Reason: Per curation guidance, generic protein binding is not retained as core; the Atg13 and TKT interactions are better represented via the Atg1 complex membership and the enzyme-activator annotation.
Supporting Evidence:
PMID:26246495
TKT–HA is efficiently pulled down by GFP-Atg1
GO:1990316 Atg1/ULK1 kinase complex
IDA
PMID:26246495
Dissecting the function of Atg1 complex in Dictyostelium aut...
ACCEPT
Summary: Atg1 is the catalytic subunit of the conserved Atg1-Atg13-Atg101 kinase complex in Dictyostelium, confirmed by yeast two-hybrid and pull-down.
Reason: Direct evidence establishes the Atg1-Atg13-Atg101 core complex, making Atg1/ULK1 kinase complex membership a core annotation.
Supporting Evidence:
PMID:26246495
The core of this assembly of proteins is formed by Atg1-Atg13-Atg101, which seems to be conserved
GO:0001878 response to yeast
IMP
PMID:27818653
Dictyostelium discoideum as a Novel Host System to Study the...
KEEP AS NON CORE
Summary: atg1-null cells show altered (increased) ability to predate yeast, implicating Atg1-dependent autophagy in the amoeba's interaction with yeast.
Reason: A downstream, autophagy-mediated host-microbe interaction phenotype; retained as non-core.
Supporting Evidence:
PMID:27818653
mutants increase (atg1-, kil1-, kil2-) or decrease (atg6-) the ability of the
GO:0035891 exit from host cell
IMP
PMID:25646440
The autophagic machinery ensures nonlytic transmission of my...
KEEP AS NON CORE
Summary: The autophagic machinery is required for nonlytic cell-to-cell transmission (ejection) of mycobacteria; impairing autophagy blocks transmission.
Reason: A specialized host-pathogen role mediated by Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:25646440
If autophagy is impaired, cell-to-cell transmission is
GO:0042742 defense response to bacterium
IMP
PMID:25646440
The autophagic machinery ensures nonlytic transmission of my...
KEEP AS NON CORE
Summary: Atg1-dependent autophagy contributes to control of intracellular mycobacteria; autophagy impairment compromises the host and permits transmission.
Reason: A cell-autonomous antibacterial defense role mediated by autophagy; downstream of the core function and retained as non-core.
Supporting Evidence:
PMID:25646440
If autophagy is impaired, cell-to-cell transmission is inhibited, the host plasma membrane becomes compromised and the host cells die
GO:0030587 sorocarp development
IMP
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
KEEP AS NON CORE
Summary: atg1 mutation causes severe developmental defects; the atg1-1 mutant fails to aggregate on bacterial lawns and arrests as loose mounds.
Reason: A well-established developmental requirement downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:14736886
does not aggregate on bacterial lawns
GO:0031288 sorocarp morphogenesis
IMP
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
KEEP AS NON CORE
Summary: atg1 mutants produce aberrant fruiting-body morphology, reflecting a requirement for Atg1 in sorocarp morphogenesis.
Reason: A developmental morphogenesis phenotype downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:14736886
Mutations in the three genes produce aberrant development
GO:0004674 protein serine/threonine kinase activity
ISS
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
ACCEPT
Summary: Ser/Thr kinase activity inferred from the conserved kinase domain; the core molecular function.
Reason: Consistent with the kinase-domain-dependent function directly demonstrated in Dictyostelium.
Supporting Evidence:
PMID:26246495
the serine/threonine kinase Atg1/ULK1
GO:0005737 cytoplasm
IDA
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
ACCEPT
Summary: Cytoplasmic localization; consistent with the diffuse cytoplasmic distribution of Atg1 reported across studies.
Reason: Cytoplasmic localization of Atg1 is well established by direct evidence.
Supporting Evidence:
PMID:26246495
Atg1 fused to GFP has been shown previously to have a general cytoplasmic pattern in Dictyostelium cells with no specific puncta localization
GO:0006995 cellular response to nitrogen starvation
IMP
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
KEEP AS NON CORE
Summary: atg1 mutants show reduced survival during nitrogen starvation, linking Atg1 to the nitrogen-starvation response.
Reason: A supported starvation-response phenotype downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:14736886
reduced survival during nitrogen starvation
GO:0016236 macroautophagy
IMP
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
ACCEPT
Summary: atg1 is required for macroautophagy in Dictyostelium, a core function.
Reason: Direct genetic evidence that Atg1 is required for macroautophagy; a core biological process.
Supporting Evidence:
PMID:14736886
genes are required for macroautophagy in Dictyostelium
GO:0030435 sporulation resulting in formation of a cellular spore
IMP
PMID:14736886
Dictyostelium macroautophagy mutants vary in the severity of...
KEEP AS NON CORE
Summary: Because Atg1 is required for normal fruiting-body development, spore formation is impaired in atg1 mutants; this is a downstream developmental consequence.
Reason: A developmental sporulation phenotype downstream of Atg1-dependent autophagy; retained as non-core.
Supporting Evidence:
PMID:14736886
Mutations in the three genes produce aberrant development

Core Functions

Atg1 is a serine/threonine protein kinase that acts as the catalytic subunit of the Atg1/ULK1 kinase complex (Atg1-Atg13-Atg101) to initiate macroautophagy, driving formation of the phagophore/autophagosome at the phagophore assembly site.

Supporting Evidence:
  • PMID:17031001
    these domains are essential for autophagy and development
  • PMID:26246495
    The core of this assembly of proteins is formed by Atg1-Atg13-Atg101, which seems to be conserved
  • PMID:14736886
    genes are required for macroautophagy in Dictyostelium

Through its kinase activity and role in initiating autophagy, Atg1 regulates the induction of macroautophagy in response to nutrient/starvation status, making it essential for starvation-induced multicellular (sorocarp) development in Dictyostelium.

Supporting Evidence:
  • PMID:26246495
    The first steps of induction and nucleation are controlled by the serine/threonine kinase Atg1/ULK1 and the class III PI3 K VPS34
  • PMID:39056773
    Atg1 increases the tolerance of D. discoideum to starvation and cAMP treatment

References

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