Functional characterisation of novel oxidative stress protection proteins in the pathogenic yeast Candida glabrata

Abstract

Candida species are important pathogens of humans and are the fourth most commonly isolated pathogen from nosocomial blood stream infections. Although Candida albicans is the principle causative agent of invasive candidiasis, the incidence of C. glabrata infection has grown rapidly. The reason for this increase is not fully understood but it is clear that the species has a higher innate tolerance to commonly administered azole antifungals, in addition to being highly tolerance to combinatorial stresses. Using S. cerevisiae, as a model due to its intrinsic sensitivity to combinatorial stress and hypothesizing that the expression of mediators of Candida glabrata combinatorial stress resistance (CSR) in S. cerevisiae would lead to induced resistance. To test this we transformed, en-masse, the Candida glabrata ORFeome into S. cerevisiae. This resulted in 1,500 CSR colonies and recovered plasmids of 118 ORFS. Sanger sequencing of these plasmids revealed a total of 29 different C. glabrata ORFS. The recovery of genes encoding known stress protectant proteins e.g. GPD1, GPD2 and TRX3 was predicted and validated the integrity of the screen. Through this screen we identified four C. glabrata unique ORFs that confer CSR and we are in the process of characterising.