Yeast Skn7p functions in a eukaryotic two-component regulatory pathway.
Previous analysis of the amino acid sequence of Skn7p, the product of the yeast SKN7 gene, revealed a potential 'receiver motif' homologous to that found in bacterial response regulators (signal-transducing effector proteins regulated by phosphorylation at a conserved aspartate residue corresponding to position D427 in Skn7p). We determined the effects of D427N and D427E mutations in Skn7p. The D427N substitution resulted in diminished activity in four independent in vivo assays of Skn7p function, while the D427E mutation enhanced Skn7p activity in these assays. Our results are consistent with predictions based on the bacterial two-component paradigm and provide experimental evidence that a receiver motif functions in regulating the activity of Skn7p in a eukaryote. Skn7p suppressed growth defects associated with a pkc1 delta mutation, raising the possibility that PKC1 might play a role in regulating Skn7p. However, epistasis experiments indicate that Skn7p does not appear to function directly downstream of the PKC1-MAP kinase pathway. Rather, Skn7p may function in a two-component signal transduction pathway that acts in parallel with the PKC1 cascade to regulate growth at the cell surface. We present evidence suggesting that Skn7p serves as a transcription factor in such a signaling pathway.
Department of Biology, McGill University, Montreal, Quebec, Canada.
J L
JL
Brown
H
H
Bussey
R C
RC
Stewart
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000235:genetics; D001483:Base Sequence; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005057:Eukaryotic Cells; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D006023:Glycoproteins / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics; D011494:Protein Kinases; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; C083328:KRE9 protein, S cerevisiae; C083962:SKN7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D001224:Aspartic Acid; D011494:Protein Kinases; D011493:Protein Kinase C; C083749:SLN1 protein, S cerevisiae