A 368-base-pair cis-acting HWP1 promoter region, HCR, of Candida albicans confers hypha-specific gene regulation and binds architectural transcription factors Nhp6 and Gcf1p.
To elucidate the molecular mechanisms controlling the expression of the hypha-specific adhesin gene HWP1 of Candida albicans, its promoter was dissected and analyzed using a green fluorescent protein reporter gene. A 368-bp region, the HWP1 control region (HCR), was critical for activation under hypha-inducing conditions and conferred developmental regulation to a heterologous ENO1 promoter. A more distal region of the promoter served to amplify the level of promoter activation. Using gel mobility shift assays, a 249-bp subregion of HCR, HCRa, was found to bind at least four proteins from crude extracts of yeasts and hyphae with differing binding patterns dependent on cell morphology. Four proteins with DNA binding activities were identified by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis after separation by anion-exchange and heparin-Sepharose chromatography. One protein with high similarity to Nhp6, an HMG1 family member in Saccharomyces cerevisiae, and another with weak similarity to an HMG-like condensation factor from Physarum polycephalum implicated changes in chromatin structure as a critical process in hypha-specific gene regulation. Proteins with strong homology to histones were also found. These studies are the first to identify proteins that bind to a DNA segment that confers developmental gene regulation in C. albicans and suggest a new model for hypha-specific gene regulation.
Kim
Samin
S
Microbiology and Molecular Pathogenesis Program, Dartmouth Medical School, Hanover, New Hampshire, USA.
Wolyniak
Michael J
MJ
Staab
Janet F
JF
Sundstrom
Paula
P
D000595:Amino Acid Sequence; D020029:Base Pairing / Q000235:genetics*; D001667:Binding, Competitive; D002176:Candida albicans / Q000166:cytology / Q000235:genetics*; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D025301:Hyphae / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D015533:Transcriptional Activation / Q000235:genetics
D004271:DNA, Fungal; D005656:Fungal Proteins; C118102:HWP1 protein, Candida albicans; D006609:High Mobility Group Proteins; D006657:Histones; D008562:Membrane Glycoproteins; D049452:Green Fluorescent Proteins