Coordination of cohesin and DNA replication observed with purified proteins

• Published in: Nature (London) 2024-02, Vol.626 (7999), p.653-660
• Main Authors: Murayama, Yasuto, Endo, Shizuko, Kurokawa, Yumiko, Kurita, Ayako, Iwasaki, Sanae, Araki, Hiroyuki
• Format: Article
• Language: English
• Subjects: 38/22; 38/77; 42/41; 42/44; 631/337/100/101; 631/337/151/2353; 631/45/147; 82/1; 82/29; 82/83; Cell Cycle Proteins - metabolism; Chromatids - metabolism; Chromosomal Proteins, Non-Histone - metabolism; Cohesin; Cohesins; Cohesion; Deoxyribonucleic acid; DNA; DNA biosynthesis; DNA helicase; DNA Replication; DNA-Binding Proteins - metabolism; Enzymatic activity; Humanities and Social Sciences; multidisciplinary; Physiology; Proteins; Replication; Replication initiation; Saccharomyces cerevisiae Proteins - metabolism; Science; Science (multidisciplinary); Topology; Unwinding; Yeast
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-023-07003-6

Two newly duplicated copies of genomic DNA are held together by the ring-shaped cohesin complex to ensure faithful inheritance of the genome during cell division 1 – 3 . Cohesin mediates sister chromatid cohesion by topologically entrapping two sister DNAs during DNA replication 4 , 5 , but how cohesion is established at the replication fork is poorly understood. Here, we studied the interplay between cohesin and replication by reconstituting a functional replisome using purified proteins. Once DNA is encircled before replication, the cohesin ring accommodates replication in its entirety, from initiation to termination, leading to topological capture of newly synthesized DNA. This suggests that topological cohesin loading is a critical molecular prerequisite to cope with replication. Paradoxically, topological loading per se is highly rate limiting and hardly occurs under the replication-competent physiological salt concentration. This inconsistency is resolved by the replisome-associated cohesion establishment factors Chl1 helicase and Ctf4 (refs. 6 , 7 ), which promote cohesin loading specifically during continuing replication. Accordingly, we found that bubble DNA, which mimics the state of DNA unwinding, induces topological cohesin loading and this is further promoted by Chl1. Thus, we propose that cohesin converts the initial electrostatic DNA-binding mode to a topological embrace when it encounters unwound DNA structures driven by enzymatic activities including replication. Together, our results show how cohesin initially responds to replication, and provide a molecular model for the establishment of sister chromatid cohesion. We study the interplay between cohesin and replication by reconstituting a functional replisome using purified proteins, showing how cohesin initially responds to replication and providing a molecular model for the establishment of sister chromatid cohesion.