The chaperone FACT and H2B ubiquitination maintain S. pombe genome architecture through genic and subtelomeric functions [ChIP-Seq]

The histone chaperone FACT and histone H2B ubiquitination (H2Bub) facilitate RNA Polymerase II passage through chromatin. It remains unknown to what extent they cooperate in vivo. Here, we used genome-wide, genetic, biochemical and microscopic approaches to dissect their interplay in the fission yeast Schizosaccharomyces pombe. We show that FACT and H2Bub repress antisense transcripts near the 5’ end and inside gene bodies, respectively. The accumulation of these transcripts accompanies with changes at genic nucleosomes in FACT and H2Bub mutants. Moreover, in the H2Bub mutant, FACT binding to histones is stabilized. Interestingly, analysis of FACT-H2Bub double mutants revealed that FACT depletion suppresses genic nucleosome loss in the H2Bub mutant. In addition, FACT, unlike H2Bub, maintains nucleosomes in intergenic regions. This is especially important for subtelomeric gene repression and in compacting chromatin into ‘knobs’. Collectively, our study demonstrates that FACT and H2Bub functionally interact with each other in a genome-context dependent manner. Further, our data indicate an involvement of FACT in higher order chromatin formation outside of euchromatin. ChIP-seq experiments in wild type, H2BK119R, pob3 and double mutant fission yeast.