A yeast heat shock transcription factor (Hsf1) mutant is defective in both Hsc82/Hsp82 synthesis and spindle pole body duplication.
Cdc28 is a cyclin-dependent protein kinase of Saccharomyces cerevisiae that is required for the G1/S and G2/M transitions of the cell division cycle. All previously described cdc28 mutants aside from cdc28-1N arrest division specifically in the G1 phase. cdc28-1N arrests division in G2/mitosis. We show here that the cdc28-109 mutant exhibits a mixed cell division arrest at 37 degrees C with cells in both the G1 and G2 phases. In order to identify proteins that functionally interact with Cdc28, we isolated mutants that are colethal with cdc28-109 at its permissive temperature. We describe here our phenotypic analysis of two such mutants, hsf1-82 and ydj1-10, that affect the heat shock transcription factor and a yeast dnaj-like protein chaperone, respectively. hsf1-82 and ydj1-10 temperature-sensitive mutants arrest the cell division cycle at several stages. However, one predominant class of cells in both mutants was arrested with a large bud and a single vertex of microtubules. Electron microscopic analysis of such hsf1-82 cells showed that they contained an unduplicated spindle pole body with an enlarged half-bridge. Two-dimensional gel electrophoresis of total cell proteins revealed that the hsf1-82 cells were specifically defective in the expression of the Hsc82 and Hsp82 proteins. Furthermore, the hsf1-82 mutation was suppressed by the HSC82 gene on a multicopy plasmid that restored Hsc82 protein to high levels in these cells. These results show that Hsf1 is required for spindle pole body duplication at 37 degrees C.
Zarzov
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P
Service de Biochemie et de Génétique Moléculaire, CEA/Saclay, Gif-sur-Yvette, France.
Boucherie
H
H
Mann
C
C
D000483:Alleles; D017489:CDC28 Protein Kinase, S cerevisiae / Q000737:chemistry / Q000235:genetics*; D002453:Cell Cycle; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005838:Genotype; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D008854:Microscopy, Electron; D008961:Models, Structural; D009154:Mutation; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012440:Saccharomyces / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus / Q000502:physiology* / Q000648:ultrastructure; D055672:Static Electricity; D014157:Transcription Factors / Q000378:metabolism*; D014404:Tubulin / Q000032:analysis
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C067168:HSF1 protein, S cerevisiae; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014404:Tubulin; D011494:Protein Kinases; C102333:histone H1 kinase; D017489:CDC28 Protein Kinase, S cerevisiae