3n9k
F229A/E292S Double Mutant of Exo-beta-1,3-glucanase from Candida albicans in Complex with Laminaritriose at 1.7 A
Structural highlights
FunctionEXG1_CANAL Major glucan 1,3-beta-glucosidase required for cell wall integrity. Beta-glucanases participate in the metabolism of beta-glucan, the main structural component of the cell wall. Can also function biosynthetically as a transglycosylase. Functions to deliver glucan from the cell to the extracellular matrix. Does not appear to impact cell wall glucan content of biofilm cells, nor is it necessary for filamentation or biofilm formation. Involved in cell-substrate and cell-cell adhesion. Adhesion to host-cell surfaces is the first critical step during mucosal infection. XOG1 is target of human antimicrobial peptide LL-37 for inhibition of cell adhesion.[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 PubMedCandida albicans exo-beta-1,3-glucanase (Exg; EC 3.2.1.58) is implicated in cell wall beta-d-glucan remodelling through its glucosyl hydrolase and/or transglucosylase activities. A pair of antiparallel phenylalanyl residues (F144 and F258) flank the entrance to the active site pocket. Various Exg mutants were studied using steady-state kinetics and crystallography aiming to understand the roles played by these residues in positioning the beta-1,3-d-glucan substrate. Mutations at the Phe-Phe entranceway demonstrated the requirement for double-sided CH/pi interactions at the +1 subsite, and the necessity for phenylalanine rather than tyrosine or tryptophan. The Tyr-Tyr double mutations introduced ordered water molecules into the entranceway. A third Phe residue (F229) nearby was evaluated as a possible +2 subsite. The inactive double mutant E292S/F229A complexed with laminaritriose has provided the first picture of substrate binding to Exg and demonstrated how the Phe-Phe arrangement acts as a clamp at the +1 subsite. The terminal sugar at the -1 site showed displacement from the position of a monosaccharide analogue with interchange of water molecules and sugar hydroxyls. An unexpected additional glucose binding site, well removed from the active site, was revealed. This site may enable Exg to associate with the branched glucan structure of the C. albicans cell wall. Carbohydrate binding sites in Candida albicans exo-beta-1,3-glucanase and the role of the Phe-Phe 'clamp' at the active site entrance.,Patrick WM, Nakatani Y, Cutfield SM, Sharpe ML, Ramsay RJ, Cutfield JF FEBS J. 2010 Sep 10. doi: 10.1111/j.1742-4658.2010.07869.x. PMID:20875088[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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