Candida albicans PKA catalytic isoforms Tpk1 and Tpk2 have different roles in stress response

ROMINA GIACOMETTI; FLORENCIA KRONBERG; MARIA SUSANA DI BERNARDO DE PASSERON

Villa Carlos Paz/Córdoba/Argentina

Congreso; XLIV Reunión Anual Sociedad Argentina de Investigación Bioquímica y Biología Molecular.; 2008

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Candida albicans PKA is coded by two catalytic subunits TPK1 and TPK2, and one regulatory subunit BCY1. In this organism the cAMP/PKA signaling pathway mediates basic cellular processes such as the yeast-to-hyphae transition and the cell cycle regulation. In Saccharomyces cerevisiae it is known that low PKA levels are associated with carbohydrates accumulation and heat and oxidative stress resistance. Previous results from our laboratory showed that C. albicans strains devoid of one or both TPK1 alleles were defective in glycogen storage, while strains lacking Tpk2p accumulated higher levels of the polysaccharide, indicating that Tpk1p and Tpk2p have opposite roles in carbohydrate metabolism. In the present study, we investigated the role of C. albicans PKA in response to saline, heat and oxidative stresses. In order to fine-tune the analysis, we performed the study on several C. albicans PKA mutants having heterozygous or homozygous deletion of TPK1 or TPK2 in a different BCY1 genetic background. Interestingly, we found that tpk1Ä strains developed a lower tolerance to saline exposure, heat shock and oxidative stress, while wild-type and tpk2Ä mutants were resistant to these stresses, indicating that both isoforms play different roles in the stress response pathway.