XXXX Tpk1p and Tpk2p isoforms differentially regulate pseudohyphal development, biofilm structure, cell aggregation and adhesins expression.

@entity268 @entity6772 @entity33962 @entity5132 @entity20883 @entity375
@entity5132 undergoes a reversible morphological transition from single @entity375 cells to pseudohyphal and hyphal filaments. In this organism, @entity268 -dependent protein kinase (PKA), coded by two catalytic subunits ( @entity33962 and @entity6772 ) and one regulatory subunit ( @entity20883 ), mediates basic cellular processes, such as the @entity375 -to-hypha transition and cell cycle regulation. It is known that both Tpk isoforms play positive roles in vegetative growth and filamentation, although distinct roles have been found in virulence, stress response and glycogen storage. However, little is known regarding the participation of Tpk1p and/or Tpk2p in pseudohyphal development. This point was addressed using several @entity5132 PKA mutants having heterozygous or homozygous deletions of @entity33962 and/or @entity6772 in different @entity20883 genetic backgrounds. We observed that under hypha-only inducing conditions, all @entity20883 heterozygous strains shifted growth toward pseudohyphal morphology; however, the pseudohypha:hypha ratio was higher in strains devoid of @entity6772 . Under pseudohypha-only inducing conditions, strains lacking @entity6772 were prone to develop short and branched pseudohyphae. In @entity6772 /\/ @entity6772 /\ strains, biofilm architecture was markedly less dense, composed of short pseudohyphae and blastospores with reduced adhesion ability to abiotic material, suggesting a significant defect in cell adherence. Immunolabelling assays showed a decreased expression of adhesins Als1p and Als3p only in the @entity6772 /\/ @entity6772 /\ strain. Complementation of this mutant with a wild-type copy of @entity6772 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.
