Mutations in the Saccharomyces cerevisiae kinase Cbk1p lead to a fertility defect that can be suppressed by the absence of Brr1p or Mpt5p (Puf5p), proteins involved in RNA metabolism.
In Saccharomyces cerevisiae the protein kinase Cbk1p is a member of the regulation of Ace2p and cellular morphogenesis (RAM) network that is involved in cell separation after cytokinesis, cell integrity, and cell polarity. In cell separation, the RAM network promotes the daughter cell-specific localization of the transcription factor Ace2p, resulting in the asymmetric transcription of genes whose products are necessary to digest the septum joining the mother and the daughter cell. RAM and SSD1 play a role in the maintenance of cell integrity. In the presence of a wild-type SSD1 gene, deletion of any RAM component causes cell lysis. We show here that some mutations of CBK1 also lead to a reduced fertility and a reduced expression of some of the mating type-specific genes. As polarized growth is an integral part of the mating process, we have isolated suppressors of the fertility defect. Among these, mutations in BRR1 or MPT5 lead to a restoration of fertility and a more-or-less pronounced restoration of polarity; they also show genetic interactions with SSD1. Our experiments reveal a multilayered system controlling aspects of cell separation, cell integrity, mating, and polarized growth.
Bourens
Myriam
M
Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, FRE3144, FRC3115, F-91198, Gif-sur-Yvette, France.
Panozzo
Cristina
C
Nowacka
Aleksandra
A
Imbeaud
Sandrine
S
Mucchielli
Marie-Hélène
MH
Herbert
Christopher J
CJ
D000483:Alleles; D002448:Cell Adhesion / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics; D004843:Epistasis, Genetic / Q000502:physiology; D005298:Fertility / Q000235:genetics*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049770:Genes, Mating Type, Fungal / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000502:physiology; D009154:Mutation / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000502:physiology; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics*; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000502:physiology; D013489:Suppression, Genetic
C102201:BRR1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; C449502:MPT5 protein, S cerevisiae; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D029701:Saccharomyces cerevisiae Proteins; C485219:Ssd1 protein, S cerevisiae; D012313:RNA; C423362:CBK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases