2w62 | pdb_00002w62
Saccharomyces cerevisiae Gas2p in complex with laminaripentaose
Structural highlights
Function[GAS2_YEAST] Splits internally a 1,3-beta-glucan molecule and transfers the newly generated reducing end (the donor) to the non-reducing end of another 1,3-beta-glucan molecule (the acceptor) forming a 1,3-beta linkage, resulting in the elongation of 1,3-beta-glucan chains in the cell wall. Involved in spore wall assembly.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedYeast 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 elongated beta(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 (betaalpha)(8) catalytic core and a separate glucan binding domain with an elongated, conserved glucan binding groove. Structures of ScGas2 complexes with different beta-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 beta(1-3) glucan chains in the yeast cell wall. Molecular mechanisms of yeast cell wall glucan remodeling.,Hurtado-Guerrero R, Schuttelkopf AW, Mouyna I, Ibrahim AF, Shepherd S, Fontaine T, Latge JP, van Aalten DM J Biol Chem. 2009 Mar 27;284(13):8461-9. Epub 2008 Dec 19. PMID:19097997[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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