National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM131754
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM115809
米国
Howard Hughes Medical Institute (HHMI)
米国
引用
ジャーナル: Sci Adv / 年: 2024 タイトル: Structure of the PCNA unloader Elg1-RFC. 著者: Fengwei Zheng / Nina Y Yao / Roxana E Georgescu / Huilin Li / Michael E O'Donnell / 要旨: During DNA replication, the proliferating cell nuclear antigen (PCNA) clamps are loaded onto primed sites for each Okazaki fragment synthesis by the AAA heteropentamer replication factor C (RFC). ...During DNA replication, the proliferating cell nuclear antigen (PCNA) clamps are loaded onto primed sites for each Okazaki fragment synthesis by the AAA heteropentamer replication factor C (RFC). PCNA encircling duplex DNA is quite stable and is removed from DNA by the dedicated clamp unloader Elg1-RFC. Here, we show the cryo-EM structure of Elg1-RFC in various states with PCNA. The structures reveal essential features of Elg1-RFC that explain how it is dedicated to PCNA unloading. Specifically, Elg1 contains two external loops that block opening of the Elg1-RFC complex for DNA binding, and an "Elg1 plug" domain that fills the central DNA binding chamber, thereby reinforcing the exclusive PCNA unloading activity of Elg1-RFC. Elg1-RFC was capable of unloading PCNA using non-hydrolyzable AMP-PNP. Both RFC and Elg1-RFC could remove PCNA from covalently closed circular DNA, indicating that PCNA unloading occurs by a mechanism that is distinct from PCNA loading. Implications for the PCNA unloading mechanism are discussed.