Clb6/Cdc28 and Cdc14 regulate phosphorylation status and cellular localization of Swi6.
Nuclear export of the transcription factor Swi6 during the budding yeast Saccharomyces cerevisiae cell cycle is known to require phosphorylation of the Swi6 serine 160 residue. We show that Clb6/Cdc28 kinase is required for this nuclear export. Furthermore, Cdc28 combined with the S-phase cyclin Clb6 specifically phosphorylates serine 160 of Swi6 in vitro. Nuclear import of Swi6 occurs concomitantly with dephosphorylation of serine 160 in late M phase. We show that Cdc14 phosphatase, the principal effector of the mitotic exit network, can trigger nuclear import of Swi6 in vivo and that Cdc14 dephosphorylates Swi6 at serine 160 in vitro. Taken together, these observations show how Swi6 dephosphorylation and phosphorylation are integrated into changes of Cdc28 activity governing entry and exit from the G1 phase of the cell cycle.
Division of Yeast Genetics, National Institute for Medical Research, London NW7 1AA, United Kingdom.
Marco
M
Geymonat
Ad
A
Spanos
Glenn P
GP
Wells
Stephen J
SJ
Smerdon
Steven G
SG
Sedgwick
D021581:Active Transport, Cell Nucleus; D017489:CDC28 Protein Kinase, S cerevisiae / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000737:chemistry; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C074860:CDC14 protein, S cerevisiae; C095227:CLB6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D019926:Cyclin B; C075111:SWI6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012694:Serine; D017489:CDC28 Protein Kinase, S cerevisiae; D017027:Protein Tyrosine Phosphatases