title: NRG1, a repressor of filamentous growth in C.albicans, is down-regulated during filament induction.
abstract: In response to a variety of external signals, the fungal pathogen Candida albicans undergoes a transition between ellipsoidal single cells (blastospores) and filaments composed of elongated cells attached end-to-end. Here we identify a DNA-binding protein, Nrg1, that represses filamentous growth in Candida probably by acting through the co-repressor Tup1. nrg1 mutant cells are predominantly filamentous under non-filament-inducing conditions and their colony morphology resembles that of tup1 mutants. We also identify two filament-specific genes, ECE1 and HWP1, whose transcription is repressed by Nrg1 under non-inducing conditions. These genes constitute a subset of those under Tup1 control, providing further evidence that Nrg1 acts by recruiting Tup1 to target genes. We show that growth in serum at 37 degrees C, a potent inducer of filamentous growth, causes a reduction of NRG1 mRNA, suggesting that filamentous growth is induced by the down-regulation of NRG1. Consistent with this idea, expression of NRG1 from a non-regulated promoter partially blocks the induction of filamentous growth.
authors.affiliation: Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, CA 94143-0414, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Braun
authors.forename: D
authors.initials: D
authors.lastname: Kadosh
authors.forename: A D
authors.initials: AD
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002175:Candida / Q000235:genetics* / Q000254:growth & development* / Q000472:pathogenicity; D003470:Culture Media; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014774:Virulence; D016335:Zinc Fingers
chemical_list: D003470:Culture Media; D004268:DNA-Binding Proteins; C082909:ECE1 protein, Candida albicans; D005656:Fungal Proteins; C118102:HWP1 protein, Candida albicans; D008562:Membrane Glycoproteins; C117881:NRG1 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins