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Indirect suppression of the wee1 mutant phenotype in Schizosaccharomyces pombe
Abstract:
For S. pombe cells mutations in the wee1 regulatory gene have been shown previously to allow cells to be smaller than normal at cell division, to endow the cell with a significantly long G1 cell cycle interval, and to alter the timing in the cell cycle of certain mutationally-defined cell cycle steps in G2. We show here that situations which lengthen S phase in proliferating wee1 mutant cells 'suppress' to varying degrees these wee1-mediated cell cycle alterations. Conditions chosen to protract S phase were use of cdc22.M45 mutant cells at semipermissive temperatures, and the presence of sub-arresting concentrations of the S phase inhibitors hydroxyurea or deoxyadenosine. Proliferation in the presence of each of these inhibitors was shown directly to result in protracted S phase. Residual cell division measurements were used to measure the cell cycle timing of G1 and G2 cell-cycle steps. The indirect suppression of the wee1 phenotype shown here can be understood in terms of the proposed role of the wee1+ gene product in coordinating cell division with cellular growth.
Insights
Lengthening S phase in wee1 mutant fission yeast suppresses cell cycle alterations. This suggests the wee1+ gene product coordinates cell division with cell growth.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Mutations in the wee1 gene of S. pombe cause smaller cell size at division.
- wee1 mutants exhibit a prolonged G1 phase and altered G2 cell cycle timing.
- The wee1+ gene product is implicated in coordinating cell division with cellular growth.
Purpose of the Study:
- To investigate the effect of lengthening S phase on wee1-mediated cell cycle alterations in S. pombe.
- To explore the role of wee1+ in cell cycle regulation and growth coordination.
Main Methods:
- Utilized cdc22.M45 mutant cells at semipermissive temperatures to protract S phase.
- Applied sub-arresting concentrations of hydroxyurea and deoxyadenosine to lengthen S phase.
- Measured residual cell division to determine cell cycle timing of G1 and G2 phases.
Main Results:
- Lengthening S phase partially or fully suppressed wee1-mediated alterations in cell size and cell cycle timing.
- Prolonged S phase was confirmed in cells treated with hydroxyurea or deoxyadenosine.
- The suppression of wee1 phenotypes was observed across different methods of S phase extension.
Conclusions:
- Extending S phase can suppress the cell cycle defects associated with wee1 mutations in S. pombe.
- These findings support the role of wee1+ in coordinating cell division with cellular growth.
- The study provides insights into cell cycle regulation and the interplay between DNA replication and cell division timing.