title: The dual specificity phosphatase Rok1 negatively regulates mating and pathogenicity in Ustilago maydis.
abstract: In the phytopathogenic fungus Ustilago maydis a conserved mitogen-activated-protein-kinase (MAPK) module regulates sexual and pathogenic development. Kpp2 is the central MAPK of this module and is required for transcriptional and morphological responses to pheromone. Upon perception of the pheromone signal Kpp2 is phosphorylated by the MAPK kinase Fuz7. Here we demonstrate that the MAPK Kpp6, which has a partially redundant function with Kpp2, is also phosphorylated by Fuz7. We show that Rok1, a putative dual specificity phosphatase for MAPK signalling, controls the phosphorylation of Kpp2 as well as of Kpp6. rok1 mutants display increased filamentation and are enhanced in virulence. The enhanced virulence is caused by more efficient appressorium formation as well as plant invasion. Overexpression of rok1 reduced conjugation hyphae formation and strongly attenuated pathogenicity. This places Rok1 in a negative feedback loop regulating Kpp2 and Kpp6 activity upon pheromone stimulation and plant colonization.
authors.affiliation: Max Planck Institute for Terrestrial Microbiology, Department Organismic Interactions, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Di Stasio
authors.forename: Thomas
authors.initials: T
authors.lastname: Brefort
authors.forename: Artemio
authors.initials: A
authors.lastname: Mendoza-Mendoza
authors.forename: Karin
authors.initials: K
authors.lastname: Münch
authors.forename: Regine
authors.initials: R
authors.lastname: Kahmann
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D013379:Substrate Specificity; D014588:Ustilago / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D014774:Virulence
chemical_list: D005656:Fungal Proteins; D020928:Mitogen-Activated Protein Kinases; C403707:kpp2 protein, Ustilago maydis; D010744:Phosphoric Monoester Hydrolases