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

Abstract

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 275 kDa in its native form, but denaturant gel electrophoresis revealed a protein with ∼130 kDa, 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 3.4 mM and 80 U (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.

The involvement of the Candida glabrata trehalase enzymes in stress resistance and gut colonization

“…We confirm the data of Zilli, Lopes [41], where it was shown that Ath1 is required for utilization of exogenous trehalose. Moreover, we show that Ath1 is present in the periplasm.…”

“…It requires divalent cations (Ca 2+ and Mn 2+ ) and has a pH optimum of 7 [34,35]. This neutral trehalase shows higher activity [39][40][41]. In S. cerevisiae, the acid trehalase enzyme is also present in the vacuole [37,38].…”

“…(CAGL0K05137g) was found to be responsible for this extracellular trehalose fermentation [41]. The Ath1 orthologues in C. albicans (CaATC1) and C. parapsilosis (CpATC1) were found to be involved in virulence and stress resistance.…”

Extracellular maltotriose hydrolysis bySaccharomyces cerevisiaecells lacking theAGT1permease

“…Another intriguing feature is how the Ima5 isomaltase reaches the extracellular/periplasmic space. The predicted IMA5 coding sequence does not encode an established signal sequence that would allow secretion of the enzyme, like is the case for invertase encoded by the SUC2 gene (Carlson et al 1983;Basso et al 2011), nor possible transmembrane segments that allow extracellular localization like for the acid trehalase in yeasts (Parrou et al 2005;Huang et al 2007;Zilli et al 2015). Nevertheless, there are examples of enzymes (e.g.…”

Metabolic constraints and quantitative design principles in gene expression during adaption of yeast to heat shock

“…This could have physiological justification. On the one hand C. glabrata is different from other yeasts in that it can only assimilate glucose and trehalose [62], [63]. This suggests that our S. cerevisiae model might not be a good estimator for trehalose turnover in C. glabrata.…”