Fission Yeast Tup1-Like Repressors Repress Chromatin Remodeling at the fbp1+ Promoter and the ade6-M26 Recombination Hotspot

Chromatin remodeling plays crucial roles in the regulation of gene expression and recombination. Transcription of the fission yeast fbp1+ gene and recombination at the meiotic recombination hotspot ade6-M26 (M26) are both regulated by cAMP responsive element (CRE)-like sequences and the CREB/ATF-type transcription factor Atf1•Pcr1. The Tup11 and Tup12 proteins, the fission yeast counterparts of the Saccharomyces cerevisiae Tup1 corepressor, are involved in glucose repression of the fbp1+ transcription. We have analyzed roles of the Tup1-like corepressors in chromatin regulation around the fbp1+ promoter and the M26 hotspot. We found that the chromatin structure around two regulatory elements for fbp1+ was remodeled under derepressed conditions in concert with the robust activation of fbp1+ transcription. Strains with tup11Δ tup12Δ double deletions grown in repressed conditions exhibited the chromatin state associated with wild-type cells grown in derepressed conditions. Interestingly, deletion of rst2+, encoding a transcription factor controlled by the cAMP-dependent kinase, alleviated the tup11Δ tup12Δ defects in chromatin regulation but not in transcription repression. The chromatin at the M26 site in mitotic cultures of a tup11Δ tup12Δ mutant resembled that of wild-type meiotic cells. These observations suggest that these fission yeast Tup1-like corepressors repress chromatin remodeling at CRE-related sequences and that Rst2 antagonizes this function.