Environmental signals controlling sexual development of the corn Smut fungus Ustilago maydis through the transcriptional regulator Prf1.
Environmental signals induce and coordinate discrete morphological transitions during sexual development of Ustilago maydis. In this fungus, mating of two compatible haploid sporidia is a prerequisite for plant infection. Cell fusion is governed by the action of pheromones and receptors, whereas the subsequent pathogenicity program is controlled by the combinatorial interaction of homeodomain proteins. The U. maydis pheromone response factor (Prf1) is a central regulator of both processes. We have analyzed the regulation of the prf1 gene and demonstrate that pheromone and cAMP signaling regulate prf1 post-transcriptionally. Transcriptional activation of prf1 was observed in the presence of carbon sources, such as glucose and fructose, allowing us to define the cis-acting element in the prf1 promoter that mediates these effects. The same element provides for negative control of prf1 gene transcription at high cAMP levels. A protein that specifically binds to this element was purified and analyzed for its role in prf1 gene regulation. On the basis of these results, we present a model in which prf1 integrates different environmental signals to control development in U. maydis.
Institut für Genetik und Mikrobiologie der Universität München, Maria-Ward-Strasse 1a, D-80638 Munich, Germany.
H A
HA
Hartmann
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J
Krüger
F
F
Lottspeich
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R
Kahmann
D000595:Amino Acid Sequence; D001483:Base Sequence; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D004271:DNA, Fungal; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010675:Pheromones / Q000378:metabolism; D010940:Plant Proteins; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012045:Regulatory Sequences, Nucleic Acid; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014588:Ustilago / Q000254:growth & development* / Q000378:metabolism
D003470:Culture Media; D004271:DNA, Fungal; D006609:High Mobility Group Proteins; C118411:MFA1 protein, S cerevisiae; D010675:Pheromones; D010940:Plant Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C121065:pheromone response factor 1, Ustilago maydis; D000242:Cyclic AMP