Defective mitosis due to a mutation in the gene for a fission yeast 26S protease subunit.
We have isolated a mutant, mts2, in the fission yeast Schizosaccharomyces pombe which is defective in chromosome segregation. The predicted amino-acid sequence of the cloned mts2+ gene product is 75% identical to the S4 subunit of the human 26S ATP/ubiquitin-dependent protease. The human S4 subunit complementary DNA expressed from an S. pombe expression plasmid can rescue an S. pombe mts2 gene disruption. Both observations demonstrate that the mts2+ gene is the S. pombe homologue of the human S4 subunit. In addition, we provide genetic evidence for a physical interaction between the S4 and the related S7 subunit in the 26S multiprotein protease. We show that polyubiquitin-conjugated proteins accumulate in the mts2 mutant at the restrictive temperature, demonstrating that the mutant has an in vivo defect in the ubiquitin-dependent proteolysis pathway. Finally, the phenotype for the mts2 mutant indicates that protein degradation by the 26S protease is essential not for entry into but for the completion of mitosis.
Gordon
C
C
MRC Human Genetics Unit, Western General Hospital, Edinburgh, UK.
McGurk
G
G
Dillon
P
P
Rosen
C
C
Hastie
N D
ND
D000595:Amino Acid Sequence; D010450:Endopeptidases / Q000235:genetics* / Q000502:physiology; D005800:Genes, Fungal / Q000502:physiology*; D005816:Genetic Complementation Test; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D012568:Schizosaccharomyces / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D029702:Schizosaccharomyces pombe Proteins; D010450:Endopeptidases; C084436:rpt2 protein, S pombe