Cloning and analysis of a Candida albicans gene that affects cell surface hydrophobicity

The opportunistic pathogenic yeast Candida albicans exhibits growth phase-d ependent changes in cell surface hydrophobicity, which has been correlated with adhesion to host tissues. Cell wall proteins that might contribute to the cell surface hydrophobicity phenotype were released by limited glucanas e digestion. These proteins were initially characterized by their rates of retention during hydrophobic interaction chromatography-high-performance li quid chromatography and used as immunogens for monoclonal antibody producti on. The present work describes the cloning and functional analysis of a C. albicans gene encoding a 38-kDa protein recognized by the monoclonal antibo dy 6C5-H4CA. The 6C5-H4CA antigen was resolved by two-dimensional electroph oresis, and a partial protein sequence was determined by mass spectrometry analysis of tryptic fragments. The obtained peptides were used to identify the gene sequence from the unannotated C. albicans DNA database. The antibo dy epitope was provisionally mapped by peptide display panning, and a pepti de sequence matching the epitope was identified in the gene sequence. The g ene sequence encodes a novel open reading frame (ORF) of unknown function t hat is highly similar to several other C. albicans ORFs and to a single Sac charomyces cerevisiae ORF, Knockout of the gene resulted in a decrease in m easurable cell surface hydrophobicity and in adhesion of C. albicans to fib ronectin, The results suggest that the 38-kDa protein is a hydrophobic surf ace protein that meditates binding to host target proteins.