The molecular function of the yeast polo-like kinase Cdc5 in Cdc14 release during early anaphase.
In the budding yeast Saccharomyces cerevisiae, Cdc14 is sequestered within the nucleolus before anaphase entry through its association with Net1/Cfi1, a nucleolar protein. Protein phosphatase PP2A(Cdc55) dephosphorylates Net1 and keeps it as a hypophosphorylated form before anaphase. Activation of the Cdc fourteen early anaphase release (FEAR) pathway after anaphase entry induces a brief Cdc14 release from the nucleolus. Some of the components in the FEAR pathway, including Esp1, Slk19, and Spo12, inactivate PP2A(Cdc55), allowing the phosphorylation of Net1 by mitotic cyclin-dependent kinase (Cdk) (Clb2-Cdk1). However, the function of another FEAR component, the Polo-like kinase Cdc5, remains elusive. Here, we show evidence indicating that Cdc5 promotes Cdc14 release primarily by stimulating the degradation of Swe1, the inhibitory kinase for mitotic Cdk. First, we found that deletion of SWE1 partially suppresses the FEAR defects in cdc5 mutants. In contrast, high levels of Swe1 impair FEAR activation. We also demonstrated that the accumulation of Swe1 in cdc5 mutants is responsible for the decreased Net1 phosphorylation. Therefore, we conclude that the down-regulation of Swe1 protein levels by Cdc5 promotes FEAR activation by relieving the inhibition on Clb2-Cdk1, the kinase for Net1 protein.
Liang
Fengshan
F
Department of Biomedical Sciences, Florida State University, Tallahassee, 32306, USA.
Jin
Fengzhi
F
Liu
Hong
H
Wang
Yanchang
Y
D000705:Anaphase / Q000502:physiology*; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D004275:DNA, Ribosomal / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
C074860:CDC14 protein, S cerevisiae; C068264:CLB1 protein, S cerevisiae; D018797:Cell Cycle Proteins; D019926:Cyclin B; D004275:DNA, Ribosomal; C119300:Net1 protein, S cerevisiae; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C081927:CDC5 protein, S cerevisiae; D016203:CDC2 Protein Kinase; D017027:Protein Tyrosine Phosphatases