title: Regulation of Hyphal Growth and N-Acetylglucosamine Catabolism by Two Transcription Factors inCandida albicans.
abstract: The amino sugar N-acetylglucosamine (GlcNAc) is increasingly recognized as an important signaling molecule in addition to its well-known structural roles at the cell surface. In the human fungal pathogenCandida albicans, GlcNAc stimulates several responses including the induction of the genes needed for its catabolism and a switch from budding to filamentous hyphal growth. We identified two genes needed for growth on GlcNAc (RON1andNGS1) and found that mutants lacking these genes fail to induce the genes needed for GlcNAc catabolism.NGS1was also important for growth on other sugars, such as maltose, butRON1appeared to be specific for GlcNAc. Both mutants could grow on nonfermentable carbon sources indicating that they do not affect mitochondrial function, which we show is important for growth on GlcNAc but not for GlcNAc induction of hyphal morphogenesis. Interestingly, both theron1Δ andngs1Δ mutants were defective in forming hyphae in response to GlcNAc, even though GlcNAc catabolism is not required for induction of hyphal morphogenesis. Theron1Δ mutant showed a partial defect in forming hyphae, which was surprising since it displayed an elevated level of filamentous cells under noninducing conditions. Theron1Δ mutant also displayed an elevated basal level of expression of genes that are normally upregulated during hyphal growth. Consistent with this, Ron1 contains an Ndt80-like DNA-binding domain, indicating that it regulates gene expression. Thus, Ron1 is a key new component of the GlcNAc response pathway that acts as both an activator and a repressor of hyphal morphogenesis.
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, New York 11794.
authors.forename: Shamoon
authors.initials: S
authors.lastname: Naseem
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, New York 11794.
authors.forename: Kyunghun
authors.initials: K
authors.lastname: Min
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, New York 11794.
authors.forename: Daniel
authors.initials: D
authors.lastname: Spitzer
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, New York 11794.
authors.forename: Justin
authors.initials: J
authors.lastname: Gardin
authors.affiliation: Department of Molecular Genetics and Microbiology, Stony Brook University, New York 11794 james.konopka@stonybrook.edu.
authors.forename: James B
authors.identifier: 0000-0001-5989-4086
authors.initials: JB
authors.lastname: Konopka
mesh_terms: D000117:Acetylglucosamine / Q000235:genetics / Q000378:metabolism*; D002176:Candida albicans / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D025301:Hyphae / Q000235:genetics* / Q000254:growth & development; D008660:Metabolism / Q000235:genetics; D009024:Morphogenesis / Q000235:genetics; D009154:Mutation; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D014157:Transcription Factors; D000117:Acetylglucosamine
keywords: Candida albicans; GlcNAc; N-acetylglucosamine; filamentous growth; germ tube; hyphal morphogenesis