ade3 (SPAC6F12.10c; synonym min11) encodes the 1323-residue single-chain (PurL-type) phosphoribosylformylglycinamidine synthase (FGAM synthase, FGAR amidotransferase, EC 6.3.5.3) of fission yeast, the ortholog of S. cerevisiae ADE6 and human PFAS. It catalyses the fourth step of de novo purine synthesis, the ATP-dependent amidation of formylglycinamide ribonucleotide (FGAR) with nitrogen from glutamine to give formylglycinamidine ribonucleotide (FGAM), using a C-terminal class I glutamine amidotransferase domain and PurM-like synthetase domains. ade3 mutants lack FGAR amidotransferase activity and require adenine. The enzyme is cytoplasmic; upon amino-acid starvation an Ade3-GFP fusion relocalises to the vacuole, and ade3 deletion impairs repression of TORC1 signalling during amino-acid starvation, a phenotype shared with the Folliculin (BFC) complex with which Ade3 co-purifies.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000329 fungal-type vacuole membrane | EXP PMID:34805795 The fission yeast FLCN/FNIP complex augments TORC1 repressio... | KEEP AS NON CORE | Summary: EXP (Kuang et al. 2021, FLCN/BFC paper): Ade3-GFP is diffuse in amino-acid-replete medium and co-localises with the FM4-64-stained vacuole after 90 min of amino-acid starvation. A real, condition-dependent observation; it is not where the enzyme carries out purine synthesis, and the resolution of the imaging does not distinguish membrane from lumen-proximal association. Reason: Starvation-induced relocalisation; not the site of the core enzymatic activity. Supporting Evidence: PMID:34805795 Similarly, we found that Ade3-GFP is diffuse in amino acid replete conditions and localizes to vacuoles when cells are starved of amino acids for 90 min (Figure 6A). |
| GO:0004642 phosphoribosylformylglycinamidine synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PANTHER PTN008493809 (FGAM synthase; S. cerevisiae ADE6, human PFAS, Drosophila Pfas). ade3 is the single-chain PurL-type FGAM synthase of S. pombe. Core MF. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt Reaction=N(2)-formyl-N(1)-(5-phospho-beta-D-ribosyl)glycinamide + L- PMID:967158 an ade3 mutants lacks FGAR amidotransferase |
| GO:0004642 phosphoribosylformylglycinamidine synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA from InterPro IPR010073 (PurL large), RHEA:17129 and EC 6.3.5.3. Correct. Note that Fluri et al. 1976 showed that ade3 mutants lack FGAR amidotransferase activity, which would support an experimental MF annotation not currently in GOA. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt IPR010073; PurL_large. PMID:967158 an ade3 mutants lacks FGAR amidotransferase |
| GO:0005737 cytoplasm | HDA PMID:10759889 Large-scale screening of intracellular protein localization ... | ACCEPT | Summary: HDA from the Ding et al. 2000 GFP-fusion genomic library screen (cytoplasm); basis of UniProt's Cytoplasm location. Supporting Evidence: PMID:10759889 we constructed a green fluorescent protein (GFP)-fusion genomic DNA library of S. pombe file:SCHPO/ade3/ade3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10759889}. |
| GO:0005737 cytoplasm | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: HDA from the Matsuyama et al. 2006 ORFeome YFP screen (cytoplasm). Consistent with a soluble de novo purine enzyme and with the diffuse Ade3-GFP signal in replete medium. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome PMID:34805795 Similarly, we found that Ade3-GFP is diffuse in amino acid replete conditions and localizes to vacuoles when cells are starved of amino acids for 90 min (Figure 6A). |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (PTN008493809; ade3 itself and human PFAS among the sources). Correct. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10759889}. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: IEA from UniProt subcellular location SL-0086 (Cytoplasm), based on Ding et al. 2000. Correct. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10759889}. |
| GO:0005794 Golgi apparatus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: HDA from the Matsuyama et al. 2006 ORFeome YFP screen (Golgi apparatus). A punctate signal in a global screen; there is no other evidence that this 145 kDa soluble enzyme associates with the Golgi, and purine biosynthetic enzymes are known to form cytoplasmic foci that could be scored as Golgi-like dots. Reason: Single high-throughput observation without a functional correlate. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome |
| GO:0006164 purine nucleotide biosynthetic process | IBA GO_REF:0000033 | TOO GENERAL | Summary: IBA (PTN008493809) purine nucleotide biosynthetic process. Correct parent of de novo IMP synthesis. Supporting Evidence: PMID:967158 an ade3 mutants lacks FGAR amidotransferase |
| GO:0006164 purine nucleotide biosynthetic process | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA IEA (ARBA00026733) purine nucleotide biosynthetic process. Correct but less specific than de novo IMP biosynthetic process. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt IPR010073; PurL_large. |
| GO:0006189 'de novo' IMP biosynthetic process | EXP PMID:17248775 Genetic Mapping in SCHIZOSACCHAROMYCES POMBE by Mitotic and ... | ACCEPT | Summary: EXP (Kohli et al. 1977 genetic mapping paper), in which ade3 is an adenine-requiring marker; the cached abstract does not discuss ade3 specifically, so defer to the curator. The adenine requirement, together with the loss of FGAR amidotransferase in ade3 mutants (Fluri et al. 1976), supports this core BP. Supporting Evidence: PMID:17248775 118 genetic markers have been assigned to 3 linkage groups PMID:967158 an ade3 mutants lacks FGAR amidotransferase |
| GO:0006189 'de novo' IMP biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: IEA from InterPro IPR010073 and UniPathway UPA00074. Correct; core BP. Supporting Evidence: file:SCHPO/ade3/ade3-uniprot.txt IPR010073; PurL_large. |
| GO:1904262 negative regulation of TORC1 signaling | EXP PMID:34805795 The fission yeast FLCN/FNIP complex augments TORC1 repressio... | KEEP AS NON CORE | Summary: EXP (Kuang et al. 2021): ade3 deletion cells are rapamycin resistant and fail to dephosphorylate the TORC1 readout Rps6 efficiently on amino-acid starvation; Ade3 co-purifies with the BFC (Folliculin) complex. The authors themselves describe the finding as surprising for an enzyme whose only known activity is purine synthesis, and it is not resolved whether Ade3 acts as a signalling component or whether the phenotype is an indirect consequence of altered purine metabolism. Defer to the curator; keep as a non-core, possibly moonlighting role. Reason: Experimentally supported but mechanistically unresolved and secondary to the enzymatic function. Supporting Evidence: PMID:34805795 Our results revealed that similar to BFC, Ade3, and Ptr2 are required for efficient repression of TORC1 in response to amino acid starvation (Figures 5C and 5D). PMID:34805795 It was surprising to discover that Ade3, a phosphoribosylformylglycinamidine synthase enzyme whose only known activity is in adenine biosynthesis, is also required for efficient repression of TORC1 when cells are starved for amino acids. |
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Download this section (compressed HTML)Q: Is the requirement for ade3 in amino-acid-starvation repression of TORC1 a direct signalling role of the protein (e.g. at the vacuole with BFC) or an indirect effect of disrupted purine/nucleotide pools in the deletion strain?
Experiment: Test whether a catalytically inactive ade3 point mutant (e.g. in the glutamine amidotransferase active site), grown with adenine, still supports TORC1 repression on amino-acid starvation and vacuolar relocalisation.
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