Results
Title

X-ray Crystal Structure of Divalent Metal-Activated β-xylosidase, RS223BX.

Authors

Jordan, Douglas; Braker, Jay; Wagschal, Kurt; Lee, Charles; Chan, Victor; Dubrovska, Ievgeniia; Anderson, Spencer; Wawrzak, Zdzislaw

Abstract

We report the X-ray crystal structure of a glycoside hydrolase family 43 β-xylosidase, RS223BX, which is strongly activated by the addition of divalent metal cations. The 2.69 Å structure reveals that the Ca cation is located at the back of the active-site pocket. The Ca is held in the active site by the carboxylate of D85, an 'extra' acid residue in comparison to other GH43 active sites. The Ca is in close contact with a histidine imidazole, which in turn is in contact with the catalytic base (D15) thus providing a mechanism for stabilizing the carboxylate anion of the base and achieve metal activation. The active-site pocket is mirrored by an 'inactive-site' pocket of unknown function that resides on the opposite side of the monomer.

Subjects

GLYCOSIDASES; XYLOSIDASES; CATIONS; X-ray crystallography; CARBOXYLATES

Publication

Applied Biochemistry & Biotechnology, 2015, Vol 177, Issue 3, p637

ISSN

0273-2289

Publication type

Academic Journal

DOI

10.1007/s12010-015-1767-z