3pe7

Publication Abstract from PubMed

Oligogalactuonate lyases (OGLs, now also classified as pectate lyase family 22) are cytoplasmic enzymes found in pectinolytic members of Enterobacteriaceae, such as the enteropathogen Yersinia enterocolitica. OGLs utilize a beta-elimination mechanism to preferentially catalyze the conversion of saturated and unsaturated digalacturonate (GalA2) into monogalaturonate (GalA) and the 4,5-unsaturated GalA-like molecule, DKI. To provide mechanistic insights into the specificity of this enzyme activity we have characterized the OGL from Y. enterocolitica, YeOGL, on oligogalacturonides and determined its three-dimensional X-ray structure to 1.65 Angstroms. The model contains a Mn2+ atom in the active site, which is coordinated by three histidines, one glutamine, and an acetate ion. The acetate mimics the binding of the uronate group of galactourono-configured substrates. These findings, in combination with enzyme kinetics and metal supplementation assays, provide a framework for modeling the active site architecture of OGL. This enzyme appears to contain a histidine for the abstraction of the lower case Greek alpha-proton in the -1 subsite, a residue that is highly conserved throughout the OGL family and represents a unique catalytic base among pectic active lyases. In addition we present a hypothesis for an emerging relationship observed between the cellular distribution of pectate lyase folding and their distinct metal coordination chemistries.

THE ACTIVE SITE OF OGL PROVIDES UNIQUE INSIGHTS INTO CYTOPLASMIC OLIGOGALACTURONATE BETA-ELIMINATION.,Abbott DW, Gilbert HJ, Boraston AB J Biol Chem. 2010 Sep 17. PMID:20851883^[1]

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