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

摘要

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 tup11 Δ tup12 Δ 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 tup11 Δ tup12 Δ defects in chromatin regulation but not in transcription repression. The chromatin at the M26 site in mitotic cultures of a tup11 Δ tup12 Δ 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.