The MAPKK kinase SteC regulates conidiophore morphology and is essential for heterokaryon formation and sexual development in the homothallic fungus Aspergillus nidulans.
Environmental signals can be transduced into intracellular responses by the action of MAP kinase cascades. Sequential phosphorylation results in the transient activation of a MAP kinase, which in turn activates certain transcription factors and thus a set of pathway-specific genes. Many steps in this cascade are conserved, and homologues have been discovered from yeast to human. We have characterized the MAPKK kinase, SteC, a homologue of Saccharomyces cerevisiae Ste11, in the filamentous fungus Aspergillus nidulans. The 886-amino-acid-long protein shares the highest similarity to Neurospora crassa Nrc-1. Deletion of the gene in A. nidulans results in a slower growth rate, the formation of more branched hyphae, altered conidiophore morphology, an inhibition of heterokaryon formation and a block of cleistothecium development. The gene is transcriptionally activated during asexual development and controls the phosphorylation of two putative MAP kinases.
Wei
Huijun
H
Department of Microbiology, University of Marburg and Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., D-35043 Marburg, Germany.
Requena
Natalia
N
Fischer
Reinhard
R
D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000502:physiology*; D002455:Cell Division / Q000235:genetics; D003001:Cloning, Molecular; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D025301:Hyphae / Q000502:physiology; D020930:MAP Kinase Kinase Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D012098:Reproduction / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014158:Transcription, Genetic
D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae; D020929:Mitogen-Activated Protein Kinase Kinases