title: Deletion of EFG1 promotes Candida albicans opaque formation responding to pH via Rim101.
abstract: Phenotypic switching in Candida albicans spontaneously generates different cellular morphologies. The reversible switching between white and opaque phenotypes is regulated by multiple regulators including Efg1 and Wor1. In mating-type-like locus (MTL) homozygous cells, the Efg1 functions as a repressor, whereas the Wor1 acts as an activator in white-opaque switching. We presented evidence that switching between white and opaque in efg1/efg1 mutant is regulated by ambient pH. In pH 6.8 media, the efg1/efg1 mutant cells exhibited opaque form, but shifted to white form in pH 4.5 media. The pH-dependent morphological switching is not blocked by further deletion of WOR1 in the efg1/efg1 mutant. Correlated with the phenotype, the opaque-phase-specific gene OP4 was induced in efg1/efg1 mutant cells when cultured in pH 6.8 media, and was repressed in pH 4.5 media. Consistently, the MTLa efg1/efg1 mutant cells could mate efficiently with MTLα cells in pH 6.8 media, but poorly in pH 4.5 media. Ectopic expression of the Rim101-405 allele in the efg1/efg1 mutant helped to bypass the pH restriction on white-opaque switching and show opaque form in both neutral and acidic media. We proposed that relief of the Efg1 repression enables C. albicans to undergo white-opaque switching in pH-dependent regulation mediated by Rim101-signaling pathway.
authors.affiliation: Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Nie
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Liu
authors.forename: Huafeng
authors.initials: H
authors.lastname: Wang
authors.forename: Jiangye
authors.initials: J
authors.lastname: Chen
mesh_terms: D015152:Blotting, Northern; D015139:Blotting, Southern; D002176:Candida albicans / Q000235:genetics / Q000254:growth & development*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D010641:Phenotype; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C121438:EFG1 protein, Candida albicans; D005656:Fungal Proteins; C489602:RIM101 protein, Candida albicans; D014157:Transcription Factors