Secretion of the acid trehalase encoded by the CgATH1 gene allows trehalose fermentation by Candida glabrata

• Main Author: Zilli D.M.W.
• Publication Date: 2015
• Other Authors: Lopes R.G., Alves S.L.*, Barros L.M., Miletti L.C., Stambuk B.U.
• Format: Article
• Language: eng
• Source: Repositório Institucional da Udesc
• dARK ID: ark:/33523/001300000h1cn
• Download full: https://repositorio.udesc.br/handle/UDESC/7920

© 2015 Elsevier GmbH.The emergent pathogen Candida glabrata differs from other yeasts because it assimilates only two sugars, glucose and the disaccharide trehalose. Since rapid identification tests are based on the ability of this yeast to rapidly hydrolyze trehalose, in this work a biochemical and molecular characterization of trehalose catabolism by this yeast was performed. Our results show that C. glabrata consumes and ferments trehalose, with parameters similar to those observed during glucose fermentation. The presence of glucose in the medium during exponential growth on trehalose revealed extracellular hydrolysis of the sugar by a cell surface acid trehalase with a pH optimum of 4.4. Approximately ~30% of the total enzymatic activity is secreted into the medium during growth on trehalose or glycerol. The secreted enzyme shows an apparent molecular mass of 275kDa in its native form, but denaturant gel electrophoresis revealed a protein with ~130kDa, which due to its migration pattern and strong binding to concanavalin A, indicates that it is probably a dimeric glycoprotein. The secreted acid trehalase shows high affinity and activity for trehalose, with Km and Vmax values of 3.4mM and 80U (mg protein)-1, respectively. Cloning of the CgATH1 gene (CAGLOK05137g) from de C. glabrata genome, a gene showing high homology to fungal acid trehalases, allowed trehalose fermentation after heterologous expression in Saccharomyces cerevisiae.