Catalytic Isoforms Tpk1 and Tpk2 of Candida albicans PKA have non redundant roles in stress response and glycogen storage

ROMINA GIACOMETTI; KRONBERG FLORENCIA; BIONDI RICARDO MIGUEL; PASSERON SUSANA

YEAST

John Wiley & Sons

Año: 2009 vol. 26 p. 273 - 285

0749-503X

Candida albicans cAMP dependent protein kinase (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 the present study, we investigated the role of C. albicans PKA in response to saline, heat and oxidative stresses as well as in glycogen storage. In order to fine-tune the analysis, we performed the study on several C. albicans PKA mutants having heterozygous or homozygous deletions of TPK1 and/or TPK2 in a different BCY1 genetic background. Interestingly, we showed that tpk1Ä/tpk1Ä strains developed a lower tolerance to saline exposure, heat shock and to oxidative stress, while wild-type and tpk2Ä/tpk2Ä mutants were resistant to these stresses, indicating that both isoforms play different roles in the stress response pathway. We also found that heterozygous and homozygous BCY1 mutants, irrespective of the TPK background were highly sensitive to heat treatment. Surprisingly, we observed that those strains devoid of one or both TPK1 alleles were defective in glycogen storage, while strains lacking Tpk2 accumulated higher levels of the polysaccharide, indicating that Tpk1 and Tpk2 have opposite roles in carbohydrate metabolism.