Nuclear-specific degradation of Far1 is controlled by the localization of the F-box protein Cdc4.
Far1 is a bifunctional protein that is required to arrest the cell cycle and establish cell polarity during yeast mating. Here we show that SCF(Cdc4) ubiquitylates Far1 in the nucleus, which in turn targets the multi-ubiquitylated protein to 26S proteasomes most likely located at the nuclear envelope. In response to mating pheromones, a fraction of Far1 was stabilized after its export into the cytoplasm by Ste21/Msn5. Preventing nuclear export destabilized Far1, while conversely cytoplasmic Far1 was stabilized, although the protein was efficiently phosphorylated in a Cdc28-Cln-dependent manner. The core SCF subunits Cdc53, Hrt1 and Skp1 were distributed in the nucleus and the cytoplasm, whereas the F-box protein Cdc4 was exclusively nuclear. A cytoplasmic form of Cdc4 was unable to complement the growth defect of cdc4-1 cells, but it was sufficient to degrade Far1 in the cytoplasm. Our results illustrate the importance of subcellular localization of F-box proteins, and provide an example of how an extracellular signal regulates protein stability at the level of substrate localization.
Blondel
M
M
Swiss Institute for Experimental Cancer Research (ISREC), Chemin des Boveresses 155, 1066 Epalinges/VD, Institute of Biochemistry, University of Lausanne (UNIL), Chemin des Boveresses 155, 1066 Epalinges/VD, Switzerland.
Galan
J M
JM
Chi
Y
Y
Lafourcade
C
C
Longaretti
C
C
Deshaies
R J
RJ
Peter
M
M
D000595:Amino Acid Sequence; D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D044783:F-Box Proteins; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006207:Half-Life; D007976:Leupeptins / Q000494:pharmacology; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism; D019913:Nuclear Localization Signals; D010447:Peptide Hydrolases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism
C080443:CDC4 protein, S cerevisiae; D018797:Cell Cycle Proteins; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins; D044783:F-Box Proteins; C081353:FAR1 protein, S cerevisiae; D005656:Fungal Proteins; D007976:Leupeptins; D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases; D017489:CDC28 Protein Kinase, S cerevisiae; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde