Candida albicans Tpk1p and Tpk2p isoforms differentially regulate pseudohyphal development

ROMINA GIACOMETTI; KRONBERG FLORENCIA; PASSERON SUSANA

Puerto Madryn, Chubut, Argentina

Congreso; XLVI Reunión Anual SAIB; 2010

Candida albicans PKA catalytic subunit is codified by two genes (TPK1 and TPK2) and the regulatory subunit by BCY1 gene. It is known that both Tpk isoforms play positive roles in vegetative growth and filamentation, though distinct roles have been found in virulence, stress response and glycogen storage. However, little is known regarding their participation in pseudohyphal development. This point was addressed using several TPK mutants in different BCY1 genetic backgrounds. We observed that under hypha-only inducing conditions, the pseudohypha/hypha ratio was higher in strains devoid of TPK2. Under pseudohypha-only inducing conditions strains lacking TPK2 were prone to develop short and branched pseudohyphae. In tpk2Ä/tpk2Ä strains, biofilm architecture was markedly less dense, with reduced adhesion ability to abiotic material like silicone catheters, suggesting a significant defect in cell adherence. Immunolabeling assays showed a decreased expression of adhesins Als1p and Als3p only in the tpk2Ä/tpk2Ä strain. Complementation of this mutant with a wild-type copy of TPK2 restored all the altered functions: pseudohyphae elongation, biofilm composition, cell aggregation and adhesins expression. Our study suggests that the Tpk2p isoform may be part of a mechanism underlying not only polarized pseudohyphal morphogenesis but also cell adherence. Supported by grants from CONICET and ANPCyT.