ExplorEnz: EC 2.3.3.21

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2.3.3.21

Accepted name:

(R)-citramalate synthase

Reaction:

acetyl-CoA + pyruvate + H₂O = CoA + (2R)-2-hydroxy-2-methylbutanedioate

Glossary:

(2R)-2-hydroxy-2-methylbutanedioate = (2R)-2-methylmalate = (–)-citramalate
3-methyl-2-oxobutanoate = α-ketoisovalerate
2-oxobutanoate = α-ketobutyrate
4-methyl-2-oxopentanoate = α-ketoisocaproate
2-oxohexanoate = α-ketopimelate
2-oxoglutarate = α-ketoglutarate

Other name(s):

CimA

Comments:

One of the enzymes involved in a pyruvate-derived pathway for isoleucine biosynthesis that is found in some bacterial and archaeal species [1,2]. The enzyme can be inhibited by isoleucine, the end-product of the pathway, but not by leucine [2]. The enzyme is highly specific for pyruvate as substrate, as the 2-oxo acids 3-methyl-2-oxobutanoate, 2-oxobutanoate, 4-methyl-2-oxopentanoate, 2-oxohexanoate and 2-oxoglutarate cannot act as substrate [1,2].

Links to other databases:

BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB

References:

1.	Howell, D.M., Xu, H. and White, R.H. (R)-citramalate synthase in methanogenic archaea. J. Bacteriol. 181 (1999) 331–333. [DOI] [PMID: 9864346]
2.	Xu, H., Zhang, Y., Guo, X., Ren, S., Staempfli, A.A., Chiao, J., Jiang, W. and Zhao, G. Isoleucine biosynthesis in Leptospira interrogans serotype 1ai strain 56601 proceeds via a threonine-independent pathway. J. Bacteriol. 186 (2004) 5400–5409. [DOI] [PMID: 15292141]

[EC 2.3.3.21 created 2007 as EC 2.3.1.182, transferred 2021 to EC 2.3.3.21]