Pheromone response in fission yeast: modulation by pat1

Summary The pat1 gene, which encodes an essential protein kinase, was identified in temperature-sensitive mutants in which, at a nonpermissive temperature, copious sporulation occurred irrespective of mating type and ploidy. In addition, at a semi-permissive temperature, conjugation was uncoupled from nutritional control, although it still required both mating types. To further characterize this intermediate effect on conjugation, we studied pheromone production and response as influenced by a pat1 mutation. Using microscopic pheromone assay conducted under starvation conditions, we observed that the pat1-114 mutant allele exerted a strong sensitizing effect towards the complementary pheromone in both mating types even at the low temperature of 23°C. The production of the pheromone was affected as well, being strongest in the P cells. Presumably the pat1 protein kinase can be tuned in to various levels of activity and thereby is able to function as a universal inhibitor of sexual differentiation in S. pombe.