Purification and characterization of recombinant malate synthase enzymes from Streptomyces coelicolor A3(2) and S. clavuligerus NRRL3585.

Malate synthases (MS) from Streptomyces coelicolor A3(2) and S. clavuligerus NRRL3585 were cloned by polymerase chain reaction into a glutathione S-transferase (GST) fusion expression vector and heterologously expressed in Escherichia coli. The fusion GST-MS construct improved the soluble expression of MS by approximately 10-fold compared to the soluble expression of nonfusion MS. With the significant improvement in levels of soluble MS, purification and subsequent cleavage of recombinant MS from GST were facilitated in this study. Using purified enzymes, optimized parameters, which achieved maximal specific activity, were established in the enzymatic assay for streptomycete MS. The average purified specific activities of S. coelicolor and S. clavuligerus MS were 26199 and 11821 nmol/mg min, respectively. Furthermore, enzymatic analysis revealed that the two streptomycete MS displayed a similar Km value for acetyl-CoA, but S. coelicolor MS had a Km value for glyoxylate that is approximately sixfold higher than S. clavuligerus MS.