Budding yeast mate in the Gl phase of the cell cycle. Cells of each mating type produce mating pheromones that interact with cell surface receptors on cells of the opposite mating type. Binding of pheromone to receptors triggers a differentiative program including altered gene transcription, altered cell morphology, and Gl cell cycle arrest. The START regulatory point in the Gl phase of the cell cycle marks a sharp transition from sensitivity to mating pheromones to resistance until the next Gl phase. We are interested in the molecular basis of this commitment event, which integrates conjugation and the cell cycle. The FAR1 gene is essential for mating pheromone arrest. We have found that FAR1 degradation is cell-cycle regulated, and degradation correlates with phosphorylation. This control and FAR1 transcriptional control result in significant accumulation of Far1 protein only in the pre-START Gl phase of the cell cycle. Cell cycle regulation of FAR1 thus can contribute to the transition from mating pheromone sensitivity to resistance at START. This implies a negative control by cell-cycle progression on machinery involved in cell cycle arrest and mating. We have begun genetic and biochemical analysis of the basis for the control of Far1 degradation. This analysis is based on our observations that Far1 phosphorylation precedes its degradation, and that an N-terminal deletion mutant of Far1 blocks degradation. We have identified an additional independent negative control of the overall pheromone signalling pathway. Transcriptional induction by mating factor of genes involved in mating is largely blocked at about the time of START, possibly by specific Cln/Cdc28 protein kinase complexes. We wish to characterize this control, first genetically and ultimately biochemically.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM049716-01A1
Application #
2187254
Study Section
Molecular Biology Study Section (MBY)
Project Start
1994-05-01
Project End
1997-04-30
Budget Start
1994-05-01
Budget End
1995-04-30
Support Year
1
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Rockefeller University
Department
Genetics
Type
Other Domestic Higher Education
DUNS #
071037113
City
New York
State
NY
Country
United States
Zip Code
10065
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Oehlen, L J; Cross, F R (1998) Potential regulation of Ste20 function by the Cln1-Cdc28 and Cln2-Cdc28 cyclin-dependent protein kinases. J Biol Chem 273:25089-97
Gartner, A; Jovanovic, A; Jeoung, D I et al. (1998) Pheromone-dependent G1 cell cycle arrest requires Far1 phosphorylation, but may not involve inhibition of Cdc28-Cln2 kinase, in vivo. Mol Cell Biol 18:3681-91
Oehlen, L J; Jeoung, D I; Cross, F R (1998) Cyclin-specific START events and the G1-phase specificity of arrest by mating factor in budding yeast. Mol Gen Genet 258:183-98
Jeoung, D I; Oehlen, L J; Cross, F R (1998) Cln3-associated kinase activity in Saccharomyces cerevisiae is regulated by the mating factor pathway. Mol Cell Biol 18:433-41
Oehlen, L J; Cross, F R (1998) The role of Cdc42 in signal transduction and mating of the budding yeast Saccharomyces cerevisiae. J Biol Chem 273:8556-9
Oehlen, L J; McKinney, J D; Cross, F R (1996) Ste12 and Mcm1 regulate cell cycle-dependent transcription of FAR1. Mol Cell Biol 16:2830-7
McKinney, J D; Cross, F R (1995) FAR1 and the G1 phase specificity of cell cycle arrest by mating factor in Saccharomyces cerevisiae. Mol Cell Biol 15:2509-16
Cross, F R (1995) Starting the cell cycle: what's the point? Curr Opin Cell Biol 7:790-7
Oehlen, B; Cross, F R (1994) Signal transduction in the budding yeast Saccharomyces cerevisiae. Curr Opin Cell Biol 6:836-41