2gdr
From Proteopedia
Crystal structure of a bacterial glutathione transferase
Overview
Prokaryotic glutathione S-transferases are as diverse as their eukaryotic counterparts but are much less well characterized. BphK from Burkholderia xenovorans LB400 consumes two GSH molecules to reductively dehalogenate chlorinated 2-hydroxy-6-oxo-6-phenyl-2,4-dienoates (HOPDAs), inhibitory polychlorinated biphenyl metabolites. Crystallographic structures of two ternary complexes of BphK were solved to a resolution of 2.1A. In the BphK-GSH-HOPDA complex, GSH and HOPDA molecules occupy the G- and H-subsites, respectively. The thiol nucleophile of the GSH molecule is positioned for SN2 attack at carbon 3 of the bound HOPDA. The respective sulfur atoms of conserved Cys-10 and the bound GSH are within 3.0A, consistent with product release and the formation of a mixed disulfide intermediate. In the BphK-(GSH)2 complex, a GSH molecule occupies each of the two subsites. The three sulfur atoms of the two GSH molecules and Cys-10 are aligned suitably for a disulfide exchange reaction that would regenerate the resting enzyme and yield disulfide-linked GSH molecules. A second conserved residue, His-106, is adjacent to the thiols of Cys-10 and the GSH bound to the G-subsite and thus may stabilize a transition state in the disulfide exchange reaction. Overall, the structures support and elaborate a proposed dehalogenation mechanism for BphK and provide insight into the plasticity of the H-subsite.
About this Structure
2GDR is a Single protein structure of sequence from Burkholderia xenovorans. Full crystallographic information is available from OCA.
Reference
Structures of ternary complexes of BphK, a bacterial glutathione S-transferase that reductively dechlorinates polychlorinated biphenyl metabolites., Tocheva EI, Fortin PD, Eltis LD, Murphy ME, J Biol Chem. 2006 Oct 13;281(41):30933-40. Epub 2006 Aug 17. PMID:16920719 Page seeded by OCA on Sun May 4 04:59:11 2008
