The isolation and characterization of nrc-1 and nrc-2, two genes encoding protein kinases that control growth and development in Neurospora crassa.
Using an insertional mutagenesis approach, a series of Neurospora crassa mutants affected in the ability to control entry into the conidiation developmental program were isolated. One such mutant, GTH16-T4, was found to lack normal vegetative hyphae and to undergo constitutive conidiation. The affected gene has been named nrc-1, for nonrepressible conidiation gene #1. The nrc-1 gene was cloned from the mutant genomic DNA by plasmid rescue, and was found to encode a protein closely related to the protein products of the Saccharomyces cerevisiae STE11 and Schizosaccharomyces pombe byr2 genes. Both of these genes encode MAPKK kinases that are necessary for sexual development in these organisms. We conclude the nrc-1 gene encodes a MAPKK kinase that functions to repress the onset of conidiation in N. crassa. A second mutant, GTH16-T17, was found to lack normal vegetative hyphae and to constitutively enter, but not complete, the conidiation program. The affected locus is referred to as nrc-2 (nonrepressible conidiation gene #2). The nrc-2 gene was cloned and found to encode a serine-threonine protein kinase. The kinase is closely related to the predicted protein products of the S. pombe kad5, and the S. cerevisiae YNRO47w and KIN82 genes, three genes that have been identified in genome sequencing projects. The N. crassa nrc-2 gene is the first member of this group of kinases for which a phenotype has been defined. We conclude a functional nrc-2-encoded serine/threonine kinase is required to repress entry into the conidiation program.
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Department of Biological Sciences, State University of New York, Buffalo, New York 14260-1300, USA.
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D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000302:isolation & purification; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D020930:MAP Kinase Kinase Kinases; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D010641:Phenotype; D011494:Protein Kinases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012568:Schizosaccharomyces / Q000201:enzymology / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics
D004271:DNA, Fungal; D005656:Fungal Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C071596:ste11 protein, S pombe; D011494:Protein Kinases; C119849:nrc-1 protein, Neurospora crassa; C119851:nrc-2 protein, Neurospora crassa; D017346:Protein Serine-Threonine Kinases; C077892:BYR2 protein, S pombe; D020930:MAP Kinase Kinase Kinases