title: Hap2 regulates the pheromone response transcription factor prf1 in Ustilago maydis.
abstract: In Ustilago maydis the pheromone signal is transmitted via a mitogen-activated protein kinase (MAP kinase) module to the transcription factor Prf1. Prf1 activates transcription of a and b mating type genes by binding to pheromone response elements (PREs) located in regulatory regions of these genes. Here we show that the CCAAT-box binding protein Hap2 from U. maydis regulates prf1 expression. Hap2 was initially identified as a potential interaction partner of the MAP kinase Kpp6 in yeast two-hybrid screens and was subsequently also shown to interact with the MAPK Kpp2. Deletion of hap2 in haploid cells abolished mating, resulting from a defect in pheromone-induced gene expression. Crosses of haploid hap2 deletion strains were completely impaired in pathogenicity. Constitutive expression of prf1 complemented the pheromone response defect in Δhap2 strains. Chromatin immunoprecipitation assays indicated that Hap2 binds directly to CCAAT motifs in the prf1 promoter. Point mutations in two putative MAPK phosphorylation sites in Hap2 attenuated the pheromone response. In a solopathogenic strain hap2 deletion affected filamentation and the mutants showed reduced pathogenicity symptoms. These data suggest that Hap2 is a novel regulator of prf1 with additional functions after cell fusion.
authors.affiliation: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., Marburg, Germany.
authors.forename: Artemio
authors.initials: A
authors.lastname: Mendoza-Mendoza
authors.forename: Anastasia
authors.initials: A
authors.lastname: Eskova
authors.forename: Carolin
authors.initials: C
authors.lastname: Weise
authors.forename: Robert
authors.initials: R
authors.lastname: Czajkowski
authors.forename: Regine
authors.initials: R
authors.lastname: Kahmann
mesh_terms: D047369:Chromatin Immunoprecipitation; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D010675:Pheromones / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D014588:Ustilago / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D003313:Zea mays / Q000382:microbiology
chemical_list: D006609:High Mobility Group Proteins; D010675:Pheromones; D010940:Plant Proteins; D014157:Transcription Factors; C121065:pheromone response factor 1, Ustilago maydis