Article info Vol. 2  No. 3   pp.  100 ~ 107
Title Structural features of archaeal β-phosphoglucomutase from hyperthermophilic Pyrococcus sp. ST04
Authors Kwang-Hyun Park, Jong-Hyun Jung, Cheon-Seok Park and Eui-Jeon Woo
Institutions Korea Research Institute of Bioscience & Biotechnology (KRIBB), Daejeon 305-806, Korea, Department of Bio-analytical Science, University of Science and Technology, Daejeon 305-333, Korea, Graduate School of Biotechnology and Institute of Life Science and Resources, Kyung Hee University, Yongin 446-701, Korea, Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea. *Correspondence: ejwoo@kribb.re.kr (E. J. Woo) or cspark@khu.ac.kr (C. S. Park)
Abstract β-Phosphoglucomutase (β-PGM) catalyzes the conversion of β-glucose-1-phosphate (β-G1P) to glucose-6-phosphate (G6P). Upon binding to the substrate, β-PGM adopts a conformational change of cap domain over the core domain with concomitant closure of the active sites located at the domain interface. Recently we have identified a novel β-PGM from Pyrococcus sp. ST04 (PsPGM) that is highly thermostable, with an optimal temperature of 95℃. The crystal structure of PsPGM shows two domains: the core domain with a typical β/α barrel-fold of haloacid dehalogenase (HAD) family, and the cap domain with α-helical bundles. The core domain contains the active site with the conserved Asp7 and cofactor Mg2+, exposing the catalytic residue to the surface. Unlike bacterial β-PGMs, the cap domain of PsPGM exists in a significantly tilted, half-closed conformation, which positions Lys82 in close proximity to the substrate binding in the absence of ligand. This unique configuration of the cap domain distinguishes this archaic enzyme from typical bacterial β-PGMs and provides a molecular basis for its enzymatic characteristics at high temperature.