RT Journal Article SR Electronic T1 Condensin facilitates sister chromatid separation in actively transcribed DNA regions by relieving the obstructive effect of transcription JF bioRxiv FD Cold Spring Harbor Laboratory SP 644799 DO 10.1101/644799 A1 Nakazawa, Norihiko A1 Arakawa, Orie A1 Yanagida, Mitsuhiro YR 2019 UL http://biorxiv.org/content/early/2019/05/24/644799.abstract AB The evolutionarily conserved protein complex, condensin, is central to chromosome dynamics, including mitotic chromosome condensation and segregation. Genome-wide localization of condensin is correlated with transcriptional activity; however, the significance of condensin accumulation in transcribed regions remains unclear. Here, we demonstrate that condensin relieves the obstructive effect of mitotic transcription on sister chromatid separation in fission yeast, Schizosaccharomyces pombe. Time-lapse visualization of sister chromatid DNA separation revealed that mutant condensin causes delayed segregation specifically at mitotically transcribed, condensin-bound gene locus, ecm33+. Contrarily, the delay was abolished by transcriptional shut-off of the actively transcribed gene. We also showed that delayed separation at a heat shock-inducible gene locus, ssa1+, in condensin mutants was significantly alleviated by deletion of the gene. Since condensin has ability to remove ssDNA-binding proteins and RNA from unwound ssDNAs or DNA-RNA hybrids in vitro, we propose a model that condensin-mediated removal of mitotic transcripts from chromosomal DNA is the primary mechanism of sister chromatid separation.