Molecular mechanisms of yeast cell wall glucan remodeling

Ramon Hurtado-Guerrero, Alexander W. Schuettelkopf, Isabelle Mouyna, Adel F. M. Ibrahim, Sharon Shepherd, Thierry Fontaine, Jean-Paul Latge, Daan M. F. van Aalten

    Research output: Contribution to journalArticlepeer-review

    58 Citations (Scopus)

    Abstract

    Yeast cell wall remodeling is controlled by the equilibrium between glycoside hydrolases, glycosyltransferases, and transglycosylases. Family 72 glycoside hydrolases (GH72) are ubiquitous in fungal organisms and are known to possess significant transglycosylase activity, producing elongatedß(1-3) glucan chains. However, the molecular mechanisms that control the balance between hydrolysis and transglycosylation in these enzymes are not understood. Here we present the first crystal structure of a glucan transglycosylase, Saccharomyces cerevisiae Gas2 (ScGas2), revealing a multidomain fold, with a (ß a)8 catalytic core and a separate glucan binding domain with an elongated, conserved glucan binding groove. Structures of ScGas2 complexes with different ß-glucan substrate/product oligosaccharides provide "snapshots" of substrate binding and hydrolysis/transglycosylation giving the first insights into the mechanisms these enzymes employ to drive beta(1-3) glucan elongation. Together with mutagenesis and analysis of reaction products, the structures suggest a "base occlusion" mechanism through which these enzymes protect the covalent protein-enzyme intermediate from a water nucleophile, thus controlling the balance between hydrolysis and transglycosylation and driving the elongation of ß(1-3) glucan chains in the yeast cell wall.

    Original languageEnglish
    Pages (from-to)8461-8469
    Number of pages9
    JournalJournal of Biological Chemistry
    Volume284
    Issue number13
    DOIs
    Publication statusPublished - 27 Mar 2009

    Keywords

    • Carbohydrate binding modules
    • pH-regulated gene
    • Saccharomyces cerevisiae
    • Xyloglucan endotransglycosylase
    • Aspergillus fumigatus
    • Candida albicans
    • Olive pollen
    • Fungal cell
    • Schizosaccharomyces pombe
    • Protein structures

    Cite this