Nucleocytoplasmic trafficking of G2/M regulators in yeast.
Nucleocytoplasmic shuttling is prevalent among many cell cycle regulators controlling the G2/M transition. Shuttling of cyclin/cyclin-dependent kinase (CDK) complexes is thought to provide access to substrates stably located in either compartment. Because cyclin/CDK shuttles between cellular compartments, an upstream regulator that is fixed in one compartment could in principle affect the entire cyclin/CDK pool. Alternatively, the regulators themselves may need to shuttle to effectively regulate their moving target. Here, we identify localization motifs in the budding yeast Swe1p (Wee1) and Mih1p (Cdc25) cell cycle regulators. Replacement of endogenous Swe1p or Mih1p with mutants impaired in nuclear import or export revealed that the nuclear pools of Swe1p and Mih1p were more effective in CDK regulation than were the cytoplasmic pools. Nevertheless, shuttling of cyclin/CDK complexes was sufficiently rapid to coordinate nuclear and cytoplasmic events even when Swe1p or Mih1p were restricted to one compartment. Additionally, we found that Swe1p nuclear export was important for its degradation. Because Swe1p degradation is regulated by cytoskeletal stress, shuttling of Swe1p between nucleus and cytoplasm serves to couple cytoplasmic stress to nuclear cyclin/CDK inhibition.
Keaton
Mignon A
MA
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
Szkotnicki
Lee
L
Marquitz
Aron R
AR
Harrison
Jake
J
Zyla
Trevin R
TR
Lew
Daniel J
DJ
D021581:Active Transport, Cell Nucleus; D000483:Alleles; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D016195:G2 Phase; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D009841:Oligonucleotides / Q000737:chemistry; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D020666:ras-GRF1
C542351:CDC25 protein, S cerevisiae; D018797:Cell Cycle Proteins; D009841:Oligonucleotides; D029701:Saccharomyces cerevisiae Proteins; D020666:ras-GRF1; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases