Binding Characteristics of epithelial adhesins from Candida glabrata

C. glabrata is a mammalian commensal yeast, which acts as a health care associated opportunistic pathogen. Due to its resistance against traditional antimycotics, the pathogen is highly emergent, and new therapeutic tools are being sought. One of the drug development targets is the epithelial adhesin (Epa) machinery, which is represented in C. glabrata by up to 23 different genes, of which the Epa1 gene is considered responsible for adhesion of fungal cells to mammalian surfaces in vitro and in vivo. These adhesins have an architecture similar to S. cerevisiae flocculins, with an N-terminal adhesive A domain, a central neck-like B domain, and an anchoring C-terminal C domain. All Epa proteins have been predicted to utilize calcium binding PA14-like domains as A domains.

Bioinformatic analysis of current data yielded variants of the Epa1 A domain representing several other members of the Epa family. All of them could be produced recombinantly and structurally characterized. High-throughput, detailed glycan binding profiles of the A domains could be generated in cooperation with the Consortium for Functional Glycomics (Atlanta, GA). By studying the best binding di-saccharide, the T-antigen (Galβ1→3GalNAc), using fluorescence titration, it was possible to obtain dissociation constants for relevant binders. Overall, detailed structural information on the binding characteristics of Epa members could be obtained, which were correlated with extensive functional data.