Genetic analysis of TAF68/61 reveals links to cell cycle regulators

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 proces ses precludes the manifestation of an arrest phenotype. In the latter situa tion, genetic analysis has the potential to reveal the involvement of TAF(I I)s in cell cycle regulation. In this report, a temperature-sensitive mutan t of TAF68161 was used to screen for high-copy dosage suppressors of its gr owth defect. Ten genes were isolated: TAF suppressor genes, TSGs 1-10. Rema rkably, 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 muta nt specifically defective for mitosis (cdc28-1N) but not an allele defectiv e for passage through start. The identification of these genes as suppresso rs of cdc28-1N has identified four unreported suppressors of this allele. M oreover, 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. Copyrig ht (C) 2001 John Wiley & Sons, Ltd.