Malate synthase (MS) catalyses the aldol condensation of glyoxylate with acetyl-CoA to form malate as part of the second step of the glyoxylate bypass and an alternative to the tricarboxylic acid cycle in bacteria, fungi and plants. There have been identified two isoforms, A and G (MSA and MSG, respectively) that differ in size and is attributed to an inserted alpha/beta domain in MSG that may have regulatory function [1,2]. In malate synthases, the TIM beta/alpha-barrel fold and the C-terminal helical domain are well conserved and the cleft between them forms the active site [1,2,3,4]. This entry represents the C-terminal domain which consists of a five-helix 'plug' connected to the barrel by an extended loop and caps the active site.

1: Atomic resolution structures of Escherichia coli and Bacillus anthracis malate synthase A: comparison with isoform G and implications for structure-based drug discovery. Lohman JR, Olson AC, Remington SJ; Protein Sci. 2008;17:1935-1945. PMID:18714089

2: Structure of the Escherichia coli malate synthase G:pyruvate:acetyl-coenzyme A abortive ternary complex at 1.95 A resolution. Anstrom DM, Kallio K, Remington SJ; Protein Sci. 2003;12:1822-1832. PMID:12930982

3: Crystal structure of Escherichia coli malate synthase G complexed with magnesium and glyoxylate at 2.0 A resolution: mechanistic implications. Howard BR, Endrizzi JA, Remington SJ; Biochemistry 2000;39:3156-3168. PMID:10715138

4: Solution NMR-derived global fold of a monomeric 82-kDa enzyme. Tugarinov V, Choy WY, Orekhov VY, Kay LE; Proc Natl Acad Sci U S A. 2005;102:622-627. PMID:15637152