Tandem Mass Spectrometric Cell Wall Proteome Profiling of a Candida albicans hwp2 Mutant Strain

Background: Candida albicans is present as part of the normal gut flora and detected in the oral cavities and GI tracts of around fifty percent of adults. Benign colonization can turn pathogenic causing a variety of mild to severe infections. In a pathogen, the cell wall and cell surface proteins are major antigenic determinants and drug targets as they are the primary structures that contact the host. Cell surface proteins perform a variety of functions necessary for virulence such as adhesion, host degradation, resistance to oxidative stress, and drug resistance. We have previously characterized Hwp2, a C. albicans cell wall adhesin shown to play a major role in the cell wall architecture and function as hwp2 mutants were deficient in chitin deposition, filamentation, adhesion and invasive growth, virulence, and resistance to oxidative stress.

Objective/method: Here, we utilized tandem mass spectrometry coupled with a bioinformatics approach to differentially profile the cell wall proteome of a wild-type strain compared to an hwp2 null mutant to determine key differentially expressed proteins.

Result: Many proteins identified exclusively in the wild-type go a long way in explaining the abovementioned phenotypes. These include virulence factors such as members of the SAP family including Sap4, Sap5, and Sap10, as well as several lipases involved in host degradation. We also identified members of the PGA family of proteins Pga28, Pga32, Pga41 and Pga50, which function in adhesion, Cht2 a chitinase involved in chitin remodeling, and several proteins that function in promoting filamentation such as Phr1, Mts1, and Rbr1.