Branched amino-acid biosynthesis is important to bacterial pathogens such as Mycobacterium tuberculosis (Mtb), a microorganism that presently causes more deaths in humans than any other prokaryotic pathogen (http://www.who.int/tb). In this study, the molecular cloning, expression, purification, crystallization and preliminary crystallographic analysis of recombinant IlvH, the small regulatory subunit of acetohydroxylic acid synthase (AHAS) in Mtb, are reported. AHAS carries out the first common reaction in the biosynthesis of valine, leucine and isoleucine. AHAS is an essential enzyme in Mtb and its inactivation leads to a lethal phenotype [Sassetti et al. (2001), Proc. Natl Acad. Sci. USA, 98, 12712–12717]. Thus, inhibitors of AHAS could potentially be developed into novel anti-Mtb therapies.
Keywords: acetolactate synthase regulatory subunit, branched amino-acid biosynthesis, Mycobacterium tuberculosis, IlvH