ATG10

ATG10 is an E2-like conjugating enzyme that drives the Atg12–Atg5 conjugation step of the autophagy ubiquitin-like cascade, thereby promoting phagophore elongation and autophagosome formation (PMID:23142976, PMID:22682742, PMID:30939964). It is recruited by the homodimeric E1 enzyme Atg7 through a noncanonical, multisite mechanism in which Atg7's unique N-terminal domain engages the Atg10 'backside' while Atg10's frontside active site is presented to the catalytic cysteine of the opposite Atg7 protomer, juxtaposing the E1 and E2 cysteines for UBL transfer (PMID:23142976, PMID:23388412). Atg10 carries an E2-core fold whose two characteristic β-strands directly recognize the C-terminal ubiquitin-like domain of Atg5, with Tyr56 and Asn114 orienting the Atg5 Lys145 side chain so that Atg12–Atg5 conjugation proceeds without a dedicated E3 enzyme (PMID:22682742). In human cells ATG10 functions at the elongation phase of autophagosome biogenesis, where its loss yields immature phagophores and impaired flux that rescue restores (PMID:30939964). ATG10 expression is tightly controlled: it is transcriptionally upregulated by HSF1, which attenuates inflammatory cytokine release in macrophages (PMID:36598250), and is repressed post-transcriptionally by the RNA-binding protein PTBP1 and by multiple miRNAs (MIR4458, MIR4667-5p, MIR4668-5p, miR-27b-3p), linking ATG10 levels to EMT-associated metastasis, drug resistance, and antibacterial autophagy (PMID:26151773, PMID:27836735, PMID:32104496). Two human isoforms exert opposing effects on autophagy flux, the canonical long ATG10 detaining peripheral autophagosomes while the short ATG10S, conjugated by IL28A, drives lysosomal docking and degradation (PMID:28900156, PMID:29670865).

1. 2012 High

   Established the catalytic basis of Atg12–Atg5 conjugation by showing how the E2 enzyme Atg10 recognizes its substrate without an E3, answering how UBL transfer specificity is achieved in autophagy.

   Evidence X-ray crystallography, NMR, mutagenesis, crosslinking and kinetics of Kluyveromyces marxianus Atg10

   PMID:22682742

   Open questions at the time

   • Atg7 recruitment mechanism not addressed here
   • human ortholog catalytic residues not directly tested
2. 2012 High

   Defined the noncanonical, multisite E1–E2 architecture by which the Atg7 homodimer recruits and positions Atg10, explaining how the catalytic cysteines are juxtaposed for thioester transfer.

   Evidence Crystal structures and mutational analysis of yeast (Atg7-Atg10)₂ complexes; additional S. cerevisiae Atg10 structure

   PMID:22993095 PMID:23142976

   Open questions at the time

   • functional role of the FR-region insertion inferred, not validated
   • dynamics of thioester transfer not resolved
3. 2012 Medium

   Revealed that Atg10-family enzymes can carry conjugation-independent functions, indicating the protein is not exclusively an autophagy E2.

   Evidence Genetic deletion with cell cycle and autophagy assays in S. pombe

   PMID:23255127

   Open questions at the time

   • molecular basis of the cell-cycle role unknown
   • conservation of this function in mammals untested
4. 2013 High

   Consolidated the principle that canonical and noncanonical UBL cascades share common catalytic logic, framing Atg10 within broader E1–E2 biochemistry.

   Evidence Crystallographic and mutational mechanistic analysis

   PMID:23388412

   Open questions at the time

   • does not address regulation of the cascade in vivo
5. 2015 Medium

   Showed ATG10 is a post-transcriptionally regulated effector of antibacterial autophagy, linking its abundance to pathogen clearance.

   Evidence miRNA microarray, 3'-UTR luciferase reporters, forced expression and bacterial survival assays in A549 cells (Burkholderia pseudomallei)

   PMID:26151773

   Open questions at the time

   • direct ATG10 enzymatic activity not measured
   • individual miRNA contributions not separated
6. 2016 Medium

   Identified PTBP1 as a direct post-transcriptional repressor of ATG10 and positioned ATG10 as a negative regulator of EMT-associated cancer cell migration.

   Evidence RNA immunoprecipitation, knockdown/ectopic expression, migration/invasion assays, EMT marker Western blots in colorectal cancer cells

   PMID:27836735

   Open questions at the time

   • whether EMT effect depends on ATG10 catalytic activity unclear
   • single lab, no in vivo metastasis data
7. 2017 Medium

   Discovered two human ATG10 isoforms with opposing effects on autophagy flux and identified IL28A as a direct partner of the short isoform.

   Evidence Isoform overexpression, autophagy flux assays, IL28A-ATG10S co-immunoprecipitation in hepatoma cells

   PMID:28900156

   Open questions at the time

   • structural basis for isoform divergence unknown
   • single Co-IP for IL28A interaction without reciprocal validation
8. 2018 Medium

   Provided in vivo corroboration that canonical ATG10 and ATG10S exert opposing effects on viral replication via their distinct autophagy roles.

   Evidence Liver-specific HCV subreplicon zebrafish model with pharmacological autophagy inhibitors and isoform overexpression

   PMID:29670865

   Open questions at the time

   • mechanism of differential autophagosome trafficking not resolved
   • relevance to authentic HCV infection untested
9. 2019 Medium

   Placed ATG10 mechanistically at the phagophore elongation step in human neurons by showing immature phagophores accumulate when ATG10 is low and resolve upon rescue.

   Evidence TEM of phagophores and ATG10 rescue in TBK1-mutant hiPSC-derived motoneurons

   PMID:30939964

   Open questions at the time

   • link between TBK1 mutation and ATG10 reduction not mechanistically defined
   • single cell model
10. 2020 Medium

    Mapped a c-Myc/miR-27b-3p/ATG10 axis controlling autophagy-dependent chemoresistance, extending ATG10 regulation upstream to transcription-factor-driven miRNA control.

    Evidence ChIP, luciferase reporters, GFP-LC3, TEM, and xenografts in colorectal cancer (oxaliplatin resistance)

    PMID:32104496

    Open questions at the time

    • direct ATG10 protein-level changes vs flux causality not fully separated
    • single lab
11. 2023 Medium

    Identified HSF1 as a direct transcriptional activator of ATG10 and connected ATG10-driven autophagy to suppression of inflammatory cytokine release.

    Evidence ChIP and EMSA for HSF1 promoter binding, siRNA/overexpression rescue, LC3 and cytokine assays in macrophages

    PMID:36598250

    Open questions at the time

    • downstream autophagic substrate of anti-inflammatory effect unknown
    • human in vivo relevance untested

• How the human ATG10 isoforms are catalytically and structurally differentiated, and whether the conjugation-independent functions seen in yeast extend to mammals, remain unresolved.
• no human ATG10 structure in the corpus
• isoform-specific trafficking mechanism undefined
• mammalian non-conjugation roles untested