title: Temperature-induced switch to the pathogenic yeast form of Histoplasma capsulatum requires Ryp1, a conserved transcriptional regulator.
abstract: Histoplasma capsulatum, a fungal pathogen of humans, switches from a filamentous spore-forming mold in the soil to a pathogenic budding-yeast form in the human host. This morphologic switch, which is exhibited by H. capsulatum and a group of evolutionarily related fungal pathogens, is regulated by temperature. Using insertional mutagenesis, we identified a gene, RYP1 (required for yeast phase growth), which is required for yeast-form growth at 37 degrees C. ryp1 mutants are constitutively filamentous irrespective of temperature. Ryp1 is a member of a family of fungal proteins that includes Wor1, a master transcriptional regulator of the white-opaque transition required for mating in Candida albicans. Ryp1 associates with its own upstream regulatory region, consistent with a direct role in transcriptional control, and both the protein and its transcript accumulate to high levels in wild-type yeast-phase cells. Microarray analysis demonstrated that Ryp1 is required for the expression of the vast majority of yeast-specific genes, including two genes linked to virulence. Thus, Ryp1 appears to be a critical transcriptional regulator of a temperature-regulated morphologic switch in H. capsulatum.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco, CA 94143-0414, USA.
authors.forename: Van Q
authors.initials: VQ
authors.lastname: Nguyen
authors.forename: Anita
authors.initials: A
authors.lastname: Sil
mesh_terms: D047369:Chromatin Immunoprecipitation; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005812:Genes, Switch; D006658:Histoplasma / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D012333:RNA, Messenger