SerC is a PLP-dependent class-V aminotransferase (EC 2.6.1.52) shared by two biosynthetic pathways. It reversibly transaminates 3-phosphohydroxypyruvate in L-serine biosynthesis and (R)-3-hydroxy-2-oxo-4-phosphooxybutanoate in DXP-dependent de novo PLP biosynthesis. In the vitamin-B6 route it forms 4-(phosphooxy)-L-threonine for the PdxA reaction.
Definition: Catalysis of the reversible reaction: 4-(phosphooxy)-L-threonine plus 2-oxoglutarate equals (R)-3-hydroxy-2-oxo-4-phosphooxybutanoate plus L-glutamate.
Justification: SerC/PdxF catalyzes this reaction in de novo PLP biosynthesis, but GO:0004648 represents only its separate phosphoserine aminotransferase reaction.
Mappings:
Supporting Evidence:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004648 O-phospho-L-serine:2-oxoglutarate transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: This term captures the phosphoserine aminotransferase reaction. Reason: GO:0004648 matches the phosphoserine reaction. SerC also catalyzes the distinct phosphohydroxythreonine reaction, for which no dedicated GO molecular-function term currently exists. Supporting Evidence: file:PSEPK/serC/serC-deep-research-openscientist.md phosphoserine aminotransferase (PSAT; EC 2.6.1.52) |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: SerC is a soluble cytoplasmic metabolic enzyme. Reason: Localization is useful context but does not distinguish either reaction. Supporting Evidence: file:PSEPK/serC/serC-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0006564 L-serine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: SerC performs the transamination step of phosphoserine synthesis. Reason: UniPathway UPA00135 and the reviewed reaction support this core role. Supporting Evidence: file:PSEPK/serC/serC-deep-research-openscientist.md the **second of three committed steps** of the phosphorylated pathway of L-serine biosynthesis |
| GO:0008615 pyridoxine biosynthetic process | IEA GO_REF:0000104 | ACCEPT | Summary: SerC performs step 3 of the erythrose-derived PNP branch. Reason: UniPathway UPA00244 assigns the phosphohydroxythreonine reaction to SerC. Supporting Evidence: file:PSEPK/serC/serC-deep-research-openscientist.md *serC* is the same protein as **PdxF** |
| GO:0036001 'de novo' pyridoxal 5'-phosphate biosynthetic process | ISS file:PSEPK/serC/serC-uniprot.txt | NEW | Summary: SerC/PdxF performs step 3 of the de novo DXP-dependent PLP route. Reason: The reviewed pathway record and the distinct RHEA:16573 reaction support the specific de novo process term. Supporting Evidence: file:PSEPK/serC/serC-uniprot.txt pyridoxine 5'-phosphate from D-erythrose 4-phosphate: step 3/5. |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: PLP is the covalently bound aminotransferase cofactor. Reason: The cofactor annotation is valid but secondary to the catalytic activity. Supporting Evidence: file:PSEPK/serC/serC-uniprot.txt Binds 1 pyridoxal phosphate per subunit. |
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Download this section (compressed HTML)The official QuickGO ontology search was queried for
'phosphohydroxythreonine aminotransferase' and for 'RHEA:16573'. It returned no
dedicated molecular-function term for the PdxF reaction. GO:0004648 covers the
separate phosphoserine aminotransferase reaction, so the proposed new term in
the review remains warranted.
Queries:
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