Elg1, the major subunit of a Replication Factor C-like complex, is critical to ensure genomic stability during DNA replication, and is implicated in controlling chromatin structure. We investigated the consequences of Elg1 loss for the dynamics of chromatin re-formation following DNA replication. Measurement of Okazaki fragment length and the micrococcal nuclease sensitivity of newly replicated DNA revealed a defect in nucleosome organization in the absence of Elg1. Using a proteomic approach to identify Elg1 binding partners, we discovered that Elg1 interacts with Rtt106, a histone chaperone implicated in replication-coupled nucleosome assembly that also regulates transcription. A central role for Elg1 is the unloading of PCNA from chromatin following DNA replication, so we examined the relative importance of Rtt106 and PCNA unloading for chromatin reassembly following DNA replication. We find that the major cause of the chromatin organization defects of an ELG1 mutant is PCNA retention on DNA following replication, with Rtt106-Elg1 interaction potentially playing a contributory role.
Bibliographical noteWe thank members of the Donaldson, Kubota, and Lorenz labs for helpful discussion, Sophie Shaw at the University of Aberdeen for data upload to Array Express and Shin-ichiro Hiraga for help with Bioinformatic analysis. This work was supported by BBSRC Grant BB/K006304/1 and Cancer Research UK Programme Award A19059 to ADD, and Wellcome Trust Grant 095062 to TOH. KS was supported by Grant-in-Aid for Scientific Research on Priority Areas (15H05970 and 15K21761) from Ministry of Education, Culture, Sports, Science and Technology, Japan
All raw-data files for MNase-Seq and ChIP-Seq data are uploaded to Array Express under accession number: E-MTAB-6985.