PKA and MAP kinase pathways play an important role in the control of meiotic development. Prior to the two meiotic divisions homologous chromosomes pair and undergo a very high rate of recombination, most of which are clustered near recombinational hotspots. The ade6-M26 hotspot of fission yeast is well characterized and requires a seven base pair DNA site (M26). Dr. Wahls and colleagues purified a heterodimeric protein, Mts1-Mts2-M26 complex serves as an enhancer of recombination. Mts1-Mts2 is a transcription factor of the CREB/ATF family and is phosphorylated by the MAP kinase Spc1. This may link the PKA and MAP kinase pathways in meiotic induction because Mts1-Mts2 is required for proper transcriptional regulation of cgs1+ and cgs2+. cgs1+ and cgs2+ harbor M26 sites in their 5' UTR and encode the regulatory subunit of PKA and cAMP phosphodiesterase, respectively. In contrast to the role in regulating the transcription of cgs1+ and cgs2+, Mts1-Mts2 do not significantly affect transcription at ade6-M26. The central hypothesis that forms the basis of this proposal is that Mts1-Mts2 are anti-repressors that provide DNA access for other proteins such as transcriptional activators and meiotic recombination enzymes through chromatin remodeling. The regulation of this process by MAP kinase and PKA pathways is also addressed. There are four specific aims: 1) to test the hypothesis that Mts1-Mts2 links the MAP kinase and PKA pathways to help induce meiotic development. 2) To these the hypothesis that transcriptional regulation and hotspot activation by Mts1-Mts2 are mechanistically related. 3) To test the hypothesis that Mts1-Mts2 recruits histone acetyltransferase activity to remodel chromatin structure and facilitate the assembly of the basal recombination machinery. 4) To test alternative hypotheses that the Mts1-Mts2-M26 complex either enhances the use of a pre-existing recombinational initiation site or creates a new initiation site. The PI request four years of support to carry out this study.
