Crystallization and preliminary X-ray analysis of alpha-­isopropylmalate synthase from Mycobacterium tuberculosis

Abstract

alpha-Isopropylmalate synthase catalyses the aldol condensation of [alpha]-­ketoisovalerate and acetyl coenzyme A to produce [alpha]-isopropylmalate. This reaction is the first committed step of leucine biosynthesis, which is interrelated with the pathways for production of the other branched-chain amino acids, valine and isoleucine. The absence of these pathways in mammals suggests that these enzymes could be useful targets for drug design against microbial pathogens. The gene for [alpha]-IPMS in Mycobacterium tuberculosis (Rv3710) has been cloned, expressed in Escherichia coli, both in native and selenomethionine-substituted forms, and crystallized. The SeMet crystals are suitable for high-resolution X-ray structural analysis. These crystals are monoclinic, with unit-cell parameters a = 54.25, b = 154.73, c = 68.82 Å, space group P21 and two molecules in the asymmetric unit. X-ray diffraction data to 2.0 Å resolution have been collected.