RBR1, a novel pH-regulated cell wall gene of Candida albicans, is repressed by RIM101 and activated by NRG1.
The transcription factor Rim101p of Candida albicans has been shown to play a major role in pH-dependent gene regulation. Rim101p is involved in cell wall biosynthesis, since it regulates PHR1 and PHR2, two almost functionally redundant cell wall glycosidases important for adaptation to either neutral or acidic habitats within the human host. To identify additional cell wall components regulated by Rim101p, we performed transcriptional profiling with a cell wall-specific DNA microarray. We showed that Rim101p contributes to the activation of known hypha-specific genes such as HWP1 and RBT1 but is also required for repression of the previously uncharacterized potential cell wall genes RBR1, RBR2, and RBR3. Further characterization of RBR1 revealed that it encodes a small glycosylphosphatidyl inositol protein that is expressed under acidic conditions predominantly at low temperature. Deletion of the gene resulted in a filamentation defect at low pH. Most interestingly, NRG1, a transcriptional repressor of hyphal growth in C. albicans, was required for RBR1 expression. The apparently activating effect of NRG1 observed in this study has not been described before. In addition, we showed that expression of NRG1 is not only temperature but also pH dependent.
Lotz
Henrike
H
Fraunhofer IGB, 70569 Stuttgart, Germany.
Sohn
Kai
K
Brunner
Herwig
H
Muhlschlegel
Fritz A
FA
Rupp
Steffen
S
D015139:Blotting, Southern; D002176:Candida albicans / Q000235:genetics* / Q000378:metabolism; D002473:Cell Wall / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D025301:Hyphae / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; C489602:RIM101 protein, Candida albicans; D012097:Repressor Proteins; D014157:Transcription Factors