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Genetic analysis of TAF68/61 reveals links to cell cycle regulators
1Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA.
Abstract:
In yeast, inactivation of certain TBP-associated factors (TAF(II)s) results in arrest at specific stages of the cell cycle. In some cases, cell cycle arrest is not observed because overlapping defects in other cellular processes precludes the manifestation of an arrest phenotype. In the latter situation, genetic analysis has the potential to reveal the involvement of TAF(II)s in cell cycle regulation. In this report, a temperature-sensitive mutant of TAF68/61 was used to screen for high-copy dosage suppressors of its growth defect. Ten genes were isolated: TAF suppressor genes, TSGs 1-10. Remarkably, most TSGs have either a genetic or a direct link to control of the G(2)/M transition. Moreover, eight of the 10 TSGs can suppress a CDC28 mutant specifically defective for mitosis (cdc28-1N) but not an allele defective for passage through start. The identification of these genes as suppressors of cdc28-1N has identified four unreported suppressors of this allele. Moreover, synthetic lethality is observed between taf68-9 and cdc28-1N. The isolation of multiple genes involved in the control of a specific phase of the cell cycle argue that the arrest phenotypes of certain TAF(II) mutants reflect their role in specifically regulating cell cycle functions.
Insights
In yeast, TAF68/61 mutations reveal new genes controlling cell cycle progression. These TAF suppressor genes (TSGs) primarily impact the G(2)/M transition, highlighting TAFs' role in cell cycle regulation.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Cell Cycle Regulation
Background:
- TBP-associated factors (TAFs) are crucial for transcription.
- In yeast, TAF inactivation can lead to cell cycle arrest.
- Some TAF defects manifest indirectly due to overlapping cellular processes.
Purpose of the Study:
- To identify genes that suppress growth defects caused by TAF68/61 inactivation.
- To elucidate the role of TAFs in cell cycle regulation using genetic screening.
- To uncover novel regulators of the G(2)/M cell cycle transition.
Main Methods:
- Construction and screening of a temperature-sensitive mutant of TAF68/61.
- High-copy dosage suppression screening to identify suppressor genes (TSGs).
- Testing TSG suppression of specific CDC28 cell cycle mutants (cdc28-1N).
- Analysis of synthetic lethality between taf68-9 and cdc28-1N.
Main Results:
- Ten TAF suppressor genes (TSGs 1-10) were isolated.
- Most TSGs are linked to the control of the G(2)/M cell cycle transition.
- Eight TSGs suppressed a mitosis-specific CDC28 mutant (cdc28-1N).
- Four novel suppressors of cdc28-1N were identified.
- Synthetic lethality was observed between taf68-9 and cdc28-1N.
Conclusions:
- TAF68/61 plays a significant role in cell cycle regulation, particularly at the G(2)/M phase.
- The identified TSGs provide new insights into the molecular mechanisms governing cell cycle progression.
- TAF(II)s are specifically involved in regulating distinct cell cycle phases.