Division of Labor between PCNA Loaders in DNA Replication and Sister Chromatid Cohesion Establishment

Hon Wing Liu,Céline Bouchoux,Mélanie Panarotto,Yasutaka Kakui,Harshil Patel,Frank Uhlmann

doi:10.1016/j.molcel.2020.03.017

Hon Wing Liu, Céline Bouchoux + Show 4 more

Open Access

https://doi.org/10.1016/j.molcel.2020.03.017

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Journal: Molecular Cell	Publication Date: Apr 10, 2020
Citations: 50	License type: cc-by

Affiliation: The Francis Crick Institute

Abstract

SummaryConcomitant with DNA replication, the chromosomal cohesin complex establishes cohesion between newly replicated sister chromatids. Several replication-fork-associated “cohesion establishment factors,” including the multifunctional Ctf18-RFC complex, aid this process in as yet unknown ways. Here, we show that Ctf18-RFC’s role in sister chromatid cohesion correlates with PCNA loading but is separable from its role in the replication checkpoint. Ctf18-RFC loads PCNA with a slight preference for the leading strand, which is dispensable for DNA replication. Conversely, the canonical Rfc1-RFC complex preferentially loads PCNA onto the lagging strand, which is crucial for DNA replication but dispensable for sister chromatid cohesion. The downstream effector of Ctf18-RFC is cohesin acetylation, which we place toward a late step during replication maturation. Our results suggest that Ctf18-RFC enriches and balances PCNA levels at the replication fork, beyond the needs of DNA replication, to promote establishment of sister chromatid cohesion and possibly other post-replicative processes.

Highlights

The physical pairing of two replicated genomic DNA molecules, known as sister chromatid cohesion, is essential for faithful segregation of genetic information to daughter cells
proliferating cell nuclear antigen (PCNA) Levels Correlate with Cohesion Establishment We previously detected Ctf18 by chromatin immunoprecipitation (ChIP) at stalled replication forks following hydroxyurea (HU) treatment (Lengronne et al, 2006), consistent with a role for Ctf18-Replication Factor-C (RFC) in replication checkpoint signaling
These results suggest that Ctf8 and Dcc1 are required for in vivo PCNA loading by Ctf18-RFC and are consistent with the idea that Ctf18-RFC acts in sister chromatid cohesion as a PCNA loader

Summary

Introduction

The physical pairing of two replicated genomic DNA molecules, known as sister chromatid cohesion, is essential for faithful segregation of genetic information to daughter cells. Sister chromatid cohesion is mediated by the chromosomal cohesin complex, a large proteinaceous ring formed of two coiled coil subunits, Smc and Smc, a kleisin subunit Scc, and additional HEAT repeat containing subunits Scc and Pds. Cohesin is loaded onto chromosomes in late G1 phase, which occurs at broad nucleosome-free regions with help of the Scc2-Scc cohesin loader complex (Munoz et al, 2019). Cohesin translocates from these loading sites, driven by active transcription, to accumulate at sites of convergent transcriptional termination (Davidson et al, 2016; Glynn et al, 2004; Lengronne et al, 2004; Ocampo-Hafalla et al, 2016). Before DNA replication, cohesin dynamically turns over on chromosomes, its unloading facilitated by Pds together with its substoichiometric binding partner Wapl (Chan et al, 2012; Gerlich et al, 2006; Lopez-Serra et al, 2013; Murayama and Uhlmann, 2015)

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