The MAPKK kinase SteC regulates conidiophore morphology and is essential for heterokaryon formation and sexual development in the homothallic fungus Aspergillus nidulans

Mol Microbiol. 2003 Mar;47(6):1577-88. doi: 10.1046/j.1365-2958.2003.03405.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Aspergillus nidulans / physiology*
  • Cell Division / genetics
  • Cloning, Molecular
  • Enzyme Activation
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Deletion
  • Gene Expression Regulation, Fungal
  • Hyphae / physiology
  • MAP Kinase Kinase Kinases / chemistry
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • Mitogen-Activated Protein Kinase Kinases / genetics
  • Mitogen-Activated Protein Kinase Kinases / metabolism*
  • Mitogen-Activated Protein Kinases / metabolism
  • Molecular Sequence Data
  • Phosphorylation
  • Reproduction / physiology
  • Saccharomyces cerevisiae Proteins
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • Transcription, Genetic


  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase Kinases
  • Ste11 protein, S cerevisiae
  • Mitogen-Activated Protein Kinase Kinases

Associated data

  • GENBANK/AJ505944