Exploring the physical and kinetic characteristics of citramalate synthase from Methanococcus jannaschii
Authors: Mohammad Firoozinia 1, Emily J Parker 2
1 School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8140, New Zealand;
2 Ferrier Research Institute, Victoria University of Wellington, Wellington, New Zealand
Isoleucine can be synthesized by a threonine-independent pathway through the action of citramalate synthase (CMS). CMS catalyzes the condensation of acetyl coenzyme A (AcCoA) and pyruvate to form citramalate as the first committed step in isoleucine biosynthesis. CMS is allosterically inhibited by isoleucine. CMS is closely related to α-isopropylmalate synthase (α-IPMS), which catalyzes the reaction between AcCoA and α-ketoisovalerate (α-KIV) in the biosynthesis of leucine. The biosynthetic pathways for the branched-chain amino acids are potential targets for drug design.
We have carried out our studies using CMS from Methanococcus jannaschii (MjCMS) to develop a greater understanding of CMS. We have also characterized the α-IPMS from Neisseria meningitidis (NmeIPMS) to determine possible functional and structural relationships with CMS. This characterization includes the evaluation of the protein structure, determination of the enzyme oligomeric structure, and thermal stability.
The activity of both wild-type (WT) MjCMS and NmeIPMS have examined, and the catalytic parameters were determined.