SNO1 (YMR095C) encodes the glutaminase subunit (PdxT/Pdx2 family, class-I glutamine amidotransferase) of the two-subunit pyridoxal 5'-phosphate (PLP) synthase of the fungal-type de novo vitamin B6 pathway. Sno1 forms a complex with the synthase subunit Snz1, which activates it. Within the complex Sno1 hydrolyses L-glutamine to L-glutamate and ammonia and channels the ammonia to Snz1, which condenses it with ribose 5-phosphate and glyceraldehyde 3-phosphate to form PLP. Sno1 is cytoplasmic and is encoded divergently from SNZ1. It is needed for optimal PLP synthesis and for growth without vitamin B6 under some conditions; the SNO2/SNO3 paralogs are induced by thiamine limitation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004359 glutaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA (contributes_to) glutaminase activity from the PdxT/SNO node PTN000774355, seeded by SNO1 itself (SGD:S000004701) and bacterial PdxT. Reason: Sno1 is the glutaminase subunit; contributes_to correctly reflects that activity requires the Snz partner. Supporting Evidence: PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone |
| GO:0004359 glutaminase activity | IDA PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | ACCEPT | Summary: The co-expressed Sno1-Snz1 complex hydrolyses glutamine (Km 3.4 mM; DON-sensitive), with Sno1 as the glutaminase; Sno1 alone is barely active, hence contributes_to. Reason: Core activity, directly measured for the yeast complex. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone |
| GO:0004359 glutaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: UniProt IEA from InterPro IPR002161/RHEA:15889/EC 3.5.1.2. Reason: Correct activity (in the context of the complex). Supporting Evidence: file:yeast/SNO1/SNO1-uniprot.txt Reaction=L-glutamine + H2O = L-glutamate + NH4(+); |
| GO:0005515 protein binding | IPI PMID:10688190 A comprehensive analysis of protein-protein interactions in ... | REMOVE | Summary: Genome-wide Y2H detected Sno1-Snz1 (IntAct). Reason: Removal does not mean the interaction is false; the Sno1-Snz1 interaction is real, but "protein binding" is uninformative. Glutaminase complex membership (GO:1903600) captures it. Supporting Evidence: PMID:10688190 These approaches resulted in the detection of 957 putative interactions involving 1,004 S. cerevisiae proteins |
| GO:0005515 protein binding | IPI PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | REMOVE | Summary: Co-expressed Sno1 and Snz1 form a glutaminase-active complex (IntAct). Reason: Real interaction; better captured by GO:1903600 glutaminase complex from the same paper. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity |
| GO:0005515 protein binding | IPI PMID:18719252 High-quality binary protein interaction map of the yeast int... | REMOVE | Summary: High-quality binary Y2H map detected Sno1-Snz1. Reason: As above; uninformative protein binding term for a real interaction captured by complex membership. Supporting Evidence: PMID:18719252 high-throughput yeast two-hybrid (Y2H) screening provides high-quality binary interaction information |
| GO:0005737 cytoplasm | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Genome-wide GFP localization scored Sno1 as cytoplasmic. Reason: Consistent with a soluble cytosolic PLP synthase. Supporting Evidence: PMID:14562095 chromosomally tagged green fluorescent protein fusion proteins |
| GO:0006543 L-glutamine catabolic process | IDA PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | KEEP AS NON CORE | Summary: ComplexPortal IDA: the Sno1-Snz1 complex hydrolyses glutamine. Reason: Glutamine hydrolysis by Sno1 is a part-reaction that supplies ammonia for PLP synthesis, not a glutamine catabolic role. Supporting Evidence: PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone |
| GO:0008614 pyridoxine metabolic process | IBA GO_REF:0000033 | MODIFY | Summary: IBA pyridoxine metabolic process from PTN000774355. SNO/PdxT supplies ammonia for de novo PLP formation; pyridoxine is not made or consumed by this enzyme. Reason: Legacy pyridoxine-specific scope; vitamin B6 biosynthesis is accurate (as in the SNO2 review). Proposed replacements: vitamin B6 biosynthetic process Supporting Evidence: PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone PMID:12271461 SNZ1 and SNO1 were both required for growth in certain conditions |
| GO:0008614 pyridoxine metabolic process | IEA GO_REF:0000117 | MODIFY | Summary: ARBA IEA pyridoxine metabolic process; same scope issue. Reason: As above. Proposed replacements: vitamin B6 biosynthetic process Supporting Evidence: PMID:12271461 SNZ1 and SNO1 were both required for growth in certain conditions |
| GO:0008615 pyridoxine biosynthetic process | IGI PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | MODIFY | Summary: SGD IGI with SNZ1: SNO1 and SNZ1 jointly form the PLP synthase and are needed for B6 prototrophy. Reason: Sound genetic finding; the product is PLP, so de novo PLP biosynthesis is the accurate process. Proposed replacements: 'de novo' pyridoxal 5'-phosphate biosynthetic process Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity PMID:12271461 SNZ1 and SNO1 were both required for growth in certain conditions |
| GO:0036001 'de novo' pyridoxal 5'-phosphate biosynthetic process | IMP PMID:30498136 SNZ3 Encodes a PLP Synthase Involved in Thiamine Synthesis i... | ACCEPT | Summary: Paxhia & Downs showed a sno1 mutant needs pyridoxine for optimal growth on minimal medium with thiamine, i.e. Sno1 is required for optimal de novo PLP synthesis. Reason: Precise and correct process term. Supporting Evidence: PMID:30498136 This result suggested that SNO1 was required for optimal PLP synthesis |
| GO:0036381 pyridoxal 5'-phosphate synthase (glutamine hydrolyzing) activity | IEA GO_REF:0000120 | ACCEPT | Summary: UniProt IEA from RHEA:31507/EC 4.3.3.6. PLP synthase activity is a property of the Snz-Sno holoenzyme; Sno1 provides the glutaminase half-reaction. Reason: Acceptable for a subunit of the holoenzyme (contributes_to would be more precise); consistent with the SNO2 review. Supporting Evidence: PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone |
| GO:0042819 vitamin B6 biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO vitamin B6 biosynthetic process (IPR002161 PdxT/SNO). Reason: Correct general process. Supporting Evidence: PMID:12271461 SNZ1 and SNO1 were both required for growth in certain conditions |
| GO:0042819 vitamin B6 biosynthetic process | IMP PMID:12271461 Functional analysis of yeast gene families involved in metab... | ACCEPT | Summary: SNO1 (not SNO2/SNO3) is required for growth without vitamin B6 in certain conditions. Reason: Direct genetic evidence. Supporting Evidence: PMID:12271461 SNZ1 and SNO1 were both required for growth in certain conditions |
| GO:0042823 pyridoxal 5'-phosphate biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA PLP biosynthetic process from PTN000774355 (SNO1, M. tuberculosis PdxT and others). Reason: Core process. Supporting Evidence: PMID:14764090 the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone |
| GO:0042823 pyridoxal 5'-phosphate biosynthetic process | IDA PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | ACCEPT | Summary: ComplexPortal IDA for the Sno1-Snz1 PLP synthase complex. Reason: Correct. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity |
| GO:0042823 pyridoxal 5'-phosphate biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: UniProt IEA from InterPro/UniPathway UPA00245. Reason: Correct. Supporting Evidence: file:yeast/SNO1/SNO1-uniprot.txt Catalyzes the hydrolysis of glutamine to glutamate and |
| GO:0043066 negative regulation of apoptotic process | IMP PMID:18355271 A TSC22-like motif defines a novel antiapoptotic protein fam... | MARK AS OVER ANNOTATED | Summary: Sno1 carries a TSC22-like 16-residue motif; overexpression delays H2O2-induced death and Ξsno1 cells are hypersensitive to H2O2. Reason: H2O2 hypersensitivity of a PLP-synthase mutant is an indirect, pleiotropic phenotype (PLP deficiency affects many enzymes); there is no mechanistic evidence that Sno1 regulates an apoptotic program. Supporting Evidence: PMID:18355271 displayed a pronounced sensitivity to the effects of H2O2 when compared to WT cells |
| GO:1903600 glutaminase complex | IBA GO_REF:0000033 | ACCEPT | Summary: IBA glutaminase complex from PTN000774355, seeded by SNO1. Reason: Correct. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity |
| GO:1903600 glutaminase complex | IPI PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | ACCEPT | Summary: Sno1 and Snz1 form a glutaminase-active complex when co-expressed (ComplexPortal / SGD IPI with SNZ1). Reason: Direct evidence for complex membership. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity |
| GO:1903600 glutaminase complex | IPI PMID:14764090 Characterization of the products of the genes SNO1 and SNZ1 ... | ACCEPT | Summary: Sno1 and Snz1 form a glutaminase-active complex when co-expressed (ComplexPortal / SGD IPI with SNZ1). Reason: Direct evidence for complex membership. Supporting Evidence: PMID:14764090 When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity |
Loading supporting contentβ¦
Download this section (compressed HTML)Protein of unconfirmed function; involved in pyridoxine metabolism; expression is induced during stationary phase; forms putative glutamine amidotransferase complex with Snz1p, with Sno1p serving as the glutaminase; sno1-Ξ affects abundance of mRNA from downstream gene CTF13
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)