Reaction: 4-phosphonooxy-L-threonine + NAD+ = 3-amino-2-oxopropyl phosphate + CO2 + NADH + H+ (overall reaction)
(1a) 4-phosphonooxy-L-threonine + NAD+ = (2S)-2-amino-3-oxo-4-phosphonooxybutanoate + NADH + H+
(1b) (2S)-2-amino-3-oxo-4-phosphonooxybutanoate = 3-amino-2-oxopropyl phosphate + CO2 (spontaneous)
For diagram, click here
Other name(s): NAD+-dependent threonine 4-phosphate dehydrogenase; L-threonine 4-phosphate dehydrogenase; 4-(phosphohydroxy)-L-threonine dehydrogenase; PdxA; 4-(phosphonooxy)-L-threonine:NAD+ oxidoreductase
Systematic name: 4-phosphonooxy-L-threonine:NAD+ oxidoreductase
Comments: The product of the reaction undergoes decarboxylation to give 3-amino-2-oxopropyl phosphate. In Escherichia coli, the coenzyme 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).
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB
CAS registry number: 230310-36-8
1. Cane, D.E., Hsiung, Y., Cornish, J.A., Robinson, J.K and Spenser, I.D. Biosynthesis of vitamine B6: The oxidation of L-threonine 4-phosphate by PdxA. J. Am. Chem. Soc. 120 (1998) 1936-1937.
2. Laber, B., Maurer, W., Scharf, S., Stepusin, K. and Schmidt, F.S. Vitamin B6 biosynthesis: formation of pyridoxine 5'-phosphate from 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose-5-phosphate by PdxA and PdxJ protein. FEBS Lett. 449 (1999) 45-48. [PMID: 10225425]
3. Sivaraman, J., Li, Y., Banks, J., Cane, D.E., Matte, A. and Cygler, M. Crystal structure of Escherichia coli PdxA, an enzyme involved in the pyridoxal phosphate biosynthesis pathway. J. Biol. Chem. 278 (2003) 43682-43690. [PMID: 12896974]