The human pre-replication complex is an open complex

• Published in: Cell Vol. 186; no. 1; pp. 98 - 111.e21
• Main Authors: Li, Jian, Dong, Jiangqing, Wang, Weitao, Yu, Daqi, Fan, Xinyu, Hui, Yan Chit, Lee, Clare S.K., Lam, Wai Hei, Alary, Nathan, Yang, Yang, Zhang, Yingyi, Zhao, Qian, Chen, Chun-Long, Tye, Bik-Kwoon, Dang, Shangyu, Zhai, Yuanliang
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 05.01.2023; Elsevier
• Subjects: Cell Cycle Proteins - metabolism; cryo-electron microscopy; Cryoelectron Microscopy; DNA; DNA Replication; DNA replication initiation; DNA-Binding Proteins - metabolism; eukaryotic cells; genome; human MCM2–7 complex; Humans; initial DNA melting; Life Sciences; Minichromosome Maintenance Proteins - metabolism; origin firing; pre-RC; replication licensing; Replication Origin; DNA replication initiation; pre-RC; initial DNA melting; human MCM2–7 complex; replication licensing; origin firing
• ISSN: 0092-8674; 1097-4172; 1097-4172
• DOI: 10.1016/j.cell.2022.12.008

In eukaryotes, DNA replication initiation requires assembly and activation of the minichromosome maintenance (MCM) 2–7 double hexamer (DH) to melt origin DNA strands. However, the mechanism for this initial melting is unknown. Here, we report a 2.59-Å cryo-electron microscopy structure of the human MCM-DH (hMCM-DH), also known as the pre-replication complex. In this structure, the hMCM-DH with a constricted central channel untwists and stretches the DNA strands such that almost a half turn of the bound duplex DNA is distorted with 1 base pair completely separated, generating an initial open structure (IOS) at the hexamer junction. Disturbing the IOS inhibits DH formation and replication initiation. Mapping of hMCM-DH footprints indicates that IOSs are distributed across the genome in large clusters aligning well with initiation zones designed for stochastic origin firing. This work unravels an intrinsic mechanism that couples DH formation with initial DNA melting to license replication initiation in human cells. [Display omitted] •Human MCM-DH melts origin DNA to form an initial open structure•The initial DNA melting is coupled with pre-RC assembly•The hMCM-DH footprints across the human genome are mapped at almost nucleotide resolution•hMCM-DH clusters and loci of active transcription are mutually exclusive Structural analysis of the human pre-replication complex provides clear insights into the initial stage of DNA melting during replication initiation in mammalian cells.