粘蛋白
康德星
DNA超螺旋
染色体分离
细胞生物学
DNA
抄写(语言学)
染色体
生物
生物物理学
遗传学
染色质
DNA复制
基因
语言学
哲学
作者
Kristian Jeppsson,Biswajit Pradhan,Takashi Sutani,Toyonori Sakata,Miki Umeda Igarashi,Davide G. Berta,Takaharu Kanno,Ryuichiro Nakato,Katsuhiko Shirahige,Eugene Kim,Camilla Sjögren
标识
DOI:10.1101/2023.06.20.545053
摘要
SUMMARY The Structural Maintenance of Chromosome (SMC) protein complexes cohesin, condensin and the Smc5/6 complex (Smc5/6) are essential for chromosome function. At the molecular level, these complexes fold DNA by loop extrusion. Accordingly, cohesin creates chromosome loops in interphase, and condensin compacts mitotic chromosomes. However, the role of Smc5/6’s recently discovered DNA loop extrusion activity is unknown. Here, we uncover that Smc5/6 associates with transcription-induced positively supercoiled chromosomal DNA at cohesin-dependent chromosome loop boundaries. Mechanistically, single-molecule imaging reveals that dimers of Smc5/6 specifically recognize the tip of positively supercoiled DNA plectonemes, and efficiently initiates loop extrusion to gather the supercoiled DNA into a large plectonemic loop. Finally, Hi-C analysis shows that Smc5/6 links chromosomal regions containing transcription-induced positive supercoiling in cis . Altogether, our findings indicate that Smc5/6 controls the three-dimensional organization of chromosomes by recognizing and initiating loop extrusion on positively supercoiled DNA.
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