title: The GRR1 gene of Candida albicans is involved in the negative control of pseudohyphal morphogenesis.
abstract: The opportunistic fungal pathogen Candida albicans can grow as yeast, pseudohyphae or true hyphae. C. albicans can switch between these morphologies in response to various environmental stimuli and this ability to switch is thought to be an important virulence trait. In Saccharomyces cerevisiae, the Grr1 protein is the substrate recognition component of an SCF ubiquitin ligase that regulates cell cycle progression, cell polarity and nutrient signaling. In this study, we have characterized the GRR1 gene of C. albicans. Deletion of GRR1 from the C. albicans genome results in a highly filamentous, pseudohyphal morphology under conditions that normally promote the yeast form of growth. Under hypha-inducing conditions, most cells lacking GRR1 retain a pseudohyphal morphology, but some cells appear to switch to hyphal-like growth and express the hypha-specific genes HWP1 and ECE1. The C. albicans GRR1 gene also complements the elongated cell morphology phenotype of an S. cerevisiae grr1Delta mutant, indicating that C. albicans GRR1 encodes a true orthologue of S. cerevisaie Grr1. These results support the hypothesis that the Grr1 protein of C. albicans, presumably as the F-box subunit of an SCF ubiquitin ligase, has an essential role in preventing the switch from the yeast cell morphology to a pseudohyphal morphology.
authors.affiliation: Department of Biological and Physical Sciences, Montana State University-Billings, 59101, USA. dbutler@msubillings.edu
authors.forename: David K
authors.initials: DK
authors.lastname: Butler
authors.forename: Ojay
authors.initials: O
authors.lastname: All
authors.forename: Joy
authors.initials: J
authors.lastname: Goffena
authors.forename: Timothy
authors.initials: T
authors.lastname: Loveless
authors.forename: Ted
authors.initials: T
authors.lastname: Wilson
authors.forename: Kurt A
authors.initials: KA
authors.lastname: Toenjes
mesh_terms: D002176:Candida albicans / Q000166:cytology* / Q000235:genetics* / Q000502:physiology; D044782:F-Box Motifs / Q000235:genetics; D044783:F-Box Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D025301:Hyphae / Q000235:genetics; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000502:physiology*
chemical_list: D044783:F-Box Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C071032:GRR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases