SGT1 encodes an essential component of the yeast kinetochore assembly pathway and a novel subunit of the SCF ubiquitin ligase complex.
We have identified SGT1 as a dosage suppressor of skp1-4, a mutation causing defects in yeast kinetochore function. Sgt1p physically associates with Skp1p in vivo and in vitro. SGT1 is an essential gene, and different sgt1 conditional mutants arrest with either a G1 or G2 DNA content. Genetic and phenotypic analyses of sgt1-3 (G2 allele) mutants support an essential role in kinetochore function. Sgt1p is required for assembling the yeast kinetochore complex, CBF3, via activation of Ctf13p. Sgt1p also associates with SCF (Skp1p/Cdc53p/F box protein) ubiquitin ligase. sgt1-5 (G1 allele) mutants are defective in Sic1p turnover in vivo and Cln1p ubiquitination in vitro. Human SGT1 rescues an sgt1 null mutation, suggesting that the function of SGT1 is conserved in evolution.
Kitagawa
K
K
Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada.
Skowyra
D
D
Elledge
S J
SJ
Harper
J W
JW
Hieter
P
P
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D004268:DNA-Binding Proteins / Q000235:genetics; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D010453:Peptide Synthases / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D044786:S-Phase Kinase-Associated Proteins; D044843:SKP Cullin F-Box Protein Ligases; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D013489:Suppression, Genetic
C092348:CEP3 protein, S cerevisiae; C081354:CTF13 protein, S cerevisiae; D018797:Cell Cycle Proteins; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D044786:S-Phase Kinase-Associated Proteins; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D044843:SKP Cullin F-Box Protein Ligases; D010453:Peptide Synthases