Srikantha T, Daniels KJ, Pujol C, Sahni N, Yi S, Soll DR. Nonsex genes in the mating type locus of Candida albicans play roles in a/α biofilm formation, including impermeability and fluconazole resistance.
PLoS Pathog 2012;
8:e1002476. [PMID:
22253594 PMCID:
PMC3257300 DOI:
10.1371/journal.ppat.1002476]
[Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 11/22/2011] [Indexed: 12/24/2022] Open
Abstract
The mating type locus (MTL) of Candida albicans contains the mating type genes and has, therefore, been assumed to play an exclusive role in the mating process. In mating-incompetent a/α cells, two of the mating type genes, MTLa1 and MTLα2, encode components of the a1-α2 corepressor that suppresses mating and switching. But the MTL locus of C. albicans also contains three apparently unrelated “nonsex” genes (NSGs), PIK, PAP and OBP, the first two essential for growth. Since it had been previously demonstrated that deleting either the a/α copy of the entire MTL locus, or either MTLa1 or MTLα2, affected virulence, we hypothesized that the NSGs in the MTL locus may also play a role in pathogenesis. Here by mutational analysis, it is demonstrated that both the mating type and nonsex genes in the MTL locus play roles in a/α biofilm formation, and that OBP is essential for impermeability and fluconazole resistance.
Most natural strains of the yeast pathogen Candida albicans are diploid and heterozygous (a/α) at the mating type locus (MTL). The MTL locus contains mating type genes and has been assumed to play roles exclusively in the mating process of a/a and α/α cells. In C. albicans, however, the MTL locus also contains three nonsex genes (NSGs), the essential phosphatidyl inositol kinase gene, PIK, the essential poly(A) polymerase gene, PAP, and the nonessential oxysterol binding protein gene, OBP. We demonstrate for the first time that both the mating type genes MTLa1 and MTLα2, and the three NSGs play non-mating roles in a/α biofilm formation and virulence. In addition, we show that the NSG OBP is necessary for impermeability and fluconazole resistance of a/α biofilms. These results demonstrate that nonsex genes as well as two mating type genes embedded in the mating type locus, play related roles in pathogenic processes unrelated to mating in a/α cells.
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