3vba

Publication Abstract from PubMed

3-Isopropylmalate/citramalate (IPM) isomerase catalyzes the second step in the leucine biosynthesis pathway. IPM isomerase from Methanococcus jannaschii is a complex protein consisting of a large (MjLeuC) and a small subunit (MjLeuD). It has broad substrate specificity, unlike other bacterial IPM isomerases. In order to understand the reasons for this broad substrate specificity, we determined the crystal structure of MjLeuD at a resolution of 2.0 A. The asymmetric unit contained 6 molecules of LeuD, including three homodimers. The overall structure had a beta/beta/alpha sandwich-fold consisting of 8 alpha-helices and 7 beta-strands. The C-terminal helix, which is important in homodimer formation, showed conformational differences between two homodimer forms of MjLeuD. In addition, we identified a hydrophobic residue (Val28) near the substrate recognition region that may explain the broad substrate specificity of IPM isomerase. Therefore, we suggest that LeuD proteins can be divided into 2 subfamilies, LeuD subfamilies 1 and 2, which show differences in overall structure and in the substrate recognition region.

Crystal structure of LeuD from Methanococcus jannaschii.,Lee EH, Cho YW, Hwang KY Biochem Biophys Res Commun. 2012 Mar 9;419(2):160-4. Epub 2012 Feb 9. PMID:22326391^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.