CHA1 encodes the catabolic L-serine/L-threonine dehydratase (deaminase) of Saccharomyces cerevisiae, a pyridoxal-phosphate-dependent member of the serine/threonine dehydratase family (EC 4.3.1.17 and 4.3.1.19) lacking the regulatory ACT domains of the biosynthetic paralog Ilv1. Cha1 deaminates L-serine to pyruvate and L-threonine to 2-oxobutanoate, releasing ammonia, which allows the cell to use these hydroxy amino acids as nitrogen sources ('catabolism of hydroxyamino acids'). The enzyme follows Michaelian kinetics, prefers serine, is not feedback-inhibited by isoleucine, and is strongly induced by serine and threonine. It is localised to mitochondria and has been found associated with mtDNA nucleoids. Cha1 and Ilv1 have distinct physiological roles but limited ability to compensate for one another.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003941 L-serine ammonia-lyase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA from PTN000034171 (serine dehydratase node, seeded by E. coli/mammalian SDS and by Cha1 itself). Correct: Cha1 prefers serine over threonine. Supporting Evidence: PMID:7042346 This enzyme which, unlike the anabolic threonine deaminase, is more active towards serine than towards threonine file:yeast/CHA1/CHA1-uniprot.txt Reaction=L-serine = pyruvate + NH4(+) |
| GO:0003941 L-serine ammonia-lyase activity | IDA PMID:7042346 Occurrence of a catabolic L-serine (L-threonine) deaminase i... | ACCEPT | Summary: Ramos & Wiame identified the cha1-dependent catabolic L-serine (L-threonine) deaminase activity, more active on serine. Core MF. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase PMID:7042346 This enzyme which, unlike the anabolic threonine deaminase, is more active towards serine than towards threonine |
| GO:0003941 L-serine ammonia-lyase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (RHEA:19169, EC 4.3.1.17); correct. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt Reaction=L-serine = pyruvate + NH4(+) |
| GO:0003941 L-serine ammonia-lyase activity | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways SERDEG-PWY (L-serine degradation). Cha1 deaminates L-serine to pyruvate + NH4+; correct. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0004794 threonine deaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA from the threonine-deaminase node PTN002459384. Cha1 deaminates threonine as well (lower activity than serine); correct. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase file:yeast/CHA1/CHA1-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+) |
| GO:0004794 threonine deaminase activity | IDA PMID:7042346 Occurrence of a catabolic L-serine (L-threonine) deaminase i... | ACCEPT | Summary: Catabolic L-serine (L-threonine) deaminase activity absent in cha1 mutants; threonine deaminase activity is the second core MF. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0004794 threonine deaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined IEA (ARBA, RHEA:22108, EC 4.3.1.19); correct. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+) |
| GO:0004794 threonine deaminase activity | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways THREOCAT2-PWY (threonine degradation). Cha1 deaminates L-threonine to 2-oxobutanoate + NH4+ in the catabolic route; correct. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0005515 protein binding | IPI PMID:11805837 Systematic identification of protein complexes in Saccharomy... | REMOVE | Summary: Interaction of Cha1 with the Rck1 protein kinase (P38622) from a large-scale HMS-PCI mass-spectrometry screen. 'protein binding' conveys no functional information; no regulatory consequence for Cha1 activity is known, so no more informative MF term can be substituted. Removal does not mean the interaction is false. Supporting Evidence: PMID:11805837 we term high-throughput mass spectrometric protein complex identification (HMS-PCI) |
| GO:0005515 protein binding | IPI PMID:17892321 Structure-templated predictions of novel protein interaction... | REMOVE | Summary: Interaction of Cha1 with the Rck1 protein kinase (P38622) from a structure-templated interaction prediction with experimental verification. 'protein binding' conveys no functional information; no regulatory consequence for Cha1 activity is known, so no more informative MF term can be substituted. Removal does not mean the interaction is false. Supporting Evidence: PMID:17892321 A number of the predicted interactions were verified experimentally |
| GO:0005739 mitochondrion | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Cha1 detected in the genome-wide GFP-fusion localization survey; consistent with its N-terminal targeting and low-throughput data. Supporting Evidence: PMID:14562095 We classify these proteins, representing 75% of the yeast proteome, into 22 distinct subcellular localization categories file:yeast/CHA1/CHA1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Cha1 detected in the PROMITO multidimensional mitochondrial proteome; consistent with its N-terminal targeting and low-throughput data. Supporting Evidence: PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified file:yeast/CHA1/CHA1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location (from GFP and proteomics) mapped to GO; correct. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: is_active_in cytosol from YeastPathways SERDEG-PWY (L-serine degradation). YeastPathways defaults its reactions to the cytosol; for Cha1 this contradicts the experimental location. Cha1 has been localised to mitochondria by GFP imaging and mitochondrial proteomics, and is associated with mtDNA nucleoids; there is no evidence for a cytosolic pool. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: is_active_in cytosol from YeastPathways THREOCAT2-PWY (threonine degradation). YeastPathways defaults its reactions to the cytosol; for Cha1 this contradicts the experimental location. Experimental localization data place Cha1 in mitochondria. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion |
| GO:0006520 amino acid metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: InterPro PLP-dehydratase domain mapping to generic 'amino acid metabolic process'; true but uninformative. Cha1's process is serine and threonine catabolism. Proposed replacements: L-serine catabolic process L-threonine catabolic process Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006565 L-serine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA; correct, Cha1 is required to use serine as nitrogen source. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006565 L-serine catabolic process | IGI PMID:7042346 Occurrence of a catabolic L-serine (L-threonine) deaminase i... | ACCEPT | Summary: cha1 was isolated in an ilv1 background (IGI with ILV1) and abolishes growth on L-serine as nitrogen source. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006565 L-serine catabolic process | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways SERDEG-PWY (L-serine degradation). Correct: Cha1 performs the deamination step of serine degradation. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006567 L-threonine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA; correct. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006567 L-threonine catabolic process | IGI PMID:7042346 Occurrence of a catabolic L-serine (L-threonine) deaminase i... | ACCEPT | Summary: cha1 selected in an ilv1 strain as unable to use L-threonine as nitrogen source; correct and core. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0006567 L-threonine catabolic process | RCA GO_REF:0000123 | ACCEPT | Summary: RCA from YeastPathways THREOCAT2-PWY (threonine degradation). Correct: Cha1 deaminates threonine to 2-oxobutanoate in threonine degradation. Supporting Evidence: PMID:7042346 This mutation, which also impairs the ability to utilize L-serine, has been denominated cha-, for 'catabolism of hydroxyamino acids' and was found to result in the lack of a catabolic L-serine (L-threonine) deaminase |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro PLP-binding-site mapping; Cha1 is a fold-type II PLP-dependent dehydratase. Correct cofactor annotation. Supporting Evidence: file:yeast/CHA1/CHA1-uniprot.txt Name=pyridoxal 5'-phosphate; Xref=ChEBI:CHEBI:597326; |
| GO:0042645 mitochondrial nucleoid | IDA PMID:15692048 Aconitase couples metabolic regulation to mitochondrial DNA ... | KEEP AS NON CORE | Summary: Chen et al. identified 22 mtDNA-associated proteins (Cha1 among them per the curator; abstract-only cache does not list them). Plausible nucleoid association of a mitochondrial metabolic enzyme; no mtDNA-related function of Cha1 is known. Defer to curator, non-core. Supporting Evidence: PMID:15692048 We have identified 22 mtDNA-associated proteins in yeast |
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