Reaction: (1) O-phospho-L-serine + 2-oxoglutarate = 3-phosphooxypyruvate + L-glutamate
(2) 4-phosphooxy-L-threonine + 2-oxoglutarate = (3R)-3-hydroxy-2-oxo-4-phosphooxybutanoate + L-glutamate
For diagram, click here or here or here for mechanism click here.
Other name(s): PSAT; phosphoserine aminotransferase; 3-phosphoserine aminotransferase; hydroxypyruvic phosphate-glutamic transaminase; L-phosphoserine aminotransferase; phosphohydroxypyruvate transaminase; phosphohydroxypyruvic-glutamic transaminase; phosphoserine aminotransferase; 3-O-phospho-L-serine:2-oxoglutarate aminotransferase; SerC; PdxC; 3PHP transaminase
Systematic name: O-phospho-L-serine:2-oxoglutarate aminotransferase
Comments: A pyridoxal-phosphate protein. This enzyme catalyses the second step in the phosphorylated pathway of serine biosynthesis in Escherichia coli [2,3]. It also catalyses the third step in the biosynthesis of the coenzyme pyridoxal 5'-phosphate in Escherichia coli (using Reaction 2 above) . In Escherichia coli, pyridoxal 5'-phosphate is synthesized de novo by a pathway that involves EC 18.104.22.168 (erythrose-4-phosphate dehydrogenase), EC 22.214.171.1240 (4-phosphoerythronate dehydrogenase), EC 126.96.36.199 (phosphoserine transaminase), EC 188.8.131.522 (4-hydroxythreonine-4-phosphate dehydrogenase), EC 184.108.40.206 (pyridoxine 5'-phosphate synthase) and EC 220.127.116.11 (with pyridoxine 5'-phosphate as substrate). Pyridoxal phosphate is the cofactor for both activities and therefore seems to be involved in its own biosynthesis . Non-phosphorylated forms of serine and threonine are not substrates .
Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9030-90-4
1. Hirsch, H. and Greenberg, D.M. Studies on phosphoserine aminotransferase of sheep brain. J. Biol. Chem. 242 (1967) 2283-2287. [PMID: 6022873]
2. Pizer, L.I. The pathway and control of serine biosynthesis in Escherichia coli. J. Biol. Chem. 238 (1963) 3934-3944. [PMID: 14086727]
3. Zhao, G. and Winkler, M.E. A novel α-ketoglutarate reductase activity of the serA-encoded 3-phosphoglycerate dehydrogenase of Escherichia coli K-12 and its possible implications for human 2-hydroxyglutaric aciduria. J. Bacteriol. 178 (1996) 232-239. [PMID: 8550422]
4. Drewke, C., Klein, M., Clade, D., Arenz, A., Müller, R. and Leistner, E. 4-O-phosphoryl-L-threonine, a substrate of the pdxC(serC) gene product involved in vitamin B6 biosynthesis. FEBS Lett. 390 (1996) 179-182. [PMID: 8706854]
5. Zhao, G. and Winkler, M.E. 4-Phospho-hydroxy-L-threonine is an obligatory intermediate in pyridoxal 5'-phosphate coenzyme biosynthesis in Escherichia coli K-12. FEMS Microbiol. Lett. 135 (1996) 275-280. [PMID: 8595869]