Genes selectively up-regulated by pheromone in white cells are involved in biofilm formation in Candida albicans.
To mate, MTL-homozygous strains of the yeast pathogen Candida albicans must switch from the white to opaque phase. Mating-competent opaque cells then release pheromone that induces polarization, a G1 block and conjugation tube formation in opaque cells of opposite mating type. Pheromone also induces mating-incompetent white cells to become adhesive and cohesive, and form thicker biofilms that facilitate mating. The pheromone response pathway of white cells shares the upstream components of that of opaque cells, but targets a different transcription factor. Here we demonstrate that the genes up-regulated by the pheromone in white cells are activated through a common cis-acting sequence, WPRE, which is distinct from the cis-acting sequence, OPRE, responsible for up-regulation in opaque cells. Furthermore, we find that these white-specific genes play roles in white cell biofilm formation, and are essential for biofilm formation in the absence of an added source of pheromone, suggesting either an autocrine or pheromone-independent mechanism. These results suggest an intimate, complex and unique relationship between switching, mating and MTL-homozygous white cell biofilm formation, the latter a presumed virulence factor in C. albicans.
Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America.
Nidhi
N
Sahni
Song
S
Yi
Karla J
KJ
Daniels
Thyagarajan
T
Srikantha
Claude
C
Pujol
David R
DR
Soll
D018441:Biofilms / Q000254:growth & development*; D015152:Blotting, Northern; D015153:Blotting, Western; D002176:Candida albicans / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D012100:Reproduction, Asexual / Q000502:physiology*; D014158:Transcription, Genetic; D015854:Up-Regulation
D005656:Fungal Proteins; D010675:Pheromones