Toggle Main Menu Toggle Search

Open Access padlockePrints

Structure of a family 15 carbohydrate-binding module in complex with xylopentaose: Evidence that xylan binds in an approximate 3-fold helical conformation

Lookup NU author(s): Lorand Szabo, He Fang Xie, Dr David Bolam, Emeritus Professor Harry Gilbert

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

The recycling of photosynthetically fixed carbon by the action of microbial glycoside hydrolases is a key biological process. The consortium of degradative enzymes involved in this process frequently display catalytic modules appended to one or more noncatalytic carbohydrate-binding modules (CBMs). CBMs play a central role in the optimization of the catalytic activity of plant cell wall hydrolases through their binding to specific plant structural polysaccharides. Despite their pivotal role in the biodegradation of plant biomass, the mechanism by which these proteins recognize their target ligands is unclear. This report describes the structure of a xylan-binding CBM (CBM15) in complex with its ligand. This module, derived from Pseudomonas cellulosa xylanase Xyn10C, binds to both soluble xylan and xylooligosaccharides. The three-dimensional crystal structure of CBM15 bound to xylopentaose has been solved by x-ray crystallography to a resolution of 1.6 Å. The protein displays a similar β-jelly roll fold to that observed in many other families of binding-modules. A groove, 20-25 Å in length, on the concave surface of one of the β-sheets presents two tryptophan residues, the faces of which are orientated at ∼240° to one another. These form-stacking interactions with the n and n+2 sugars of xylopentaose complementing the approximate 3-fold helical structure of this ligand in the binding cleft of CBM15. In four of the five observed binding subsites, the 2′ and 3′ hydroxyls of the bound ligand are solvent-exposed, providing an explanation for the capacity of this xylan-binding CBM to accommodate the highly decorated xylans found in the plant cell wall.


Publication metadata

Author(s): Szabó L, Jamal S, Xie H, Charnock S, Bolam DN, Gilbert HJ, Davies G

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2001

Volume: 276

Issue: 52

Pages: 49061-49065

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X

Publisher: American Society for Biochemistry and Molecular Biology

URL: http://dx.doi.org/10.1074/jbc.M109558200

DOI: 10.1074/jbc.M109558200

PubMed id: 11598143


Altmetrics

Altmetrics provided by Altmetric


Share