6RQC

Cryo-EM structure of an MCM loading intermediate

これはPDB形式変換不可エントリーです。

6RQC の概要

• エントリーDOI: 10.2210/pdb6rqc/pdb
• EMDBエントリー: 4980
• 分子名称: Origin recognition complex subunit 1, Minichromosome maintenance protein 5, DNA replication licensing factor MCM6, ... (18 entities in total)
• 機能のキーワード: dna replication, origin licensing, mcm2-7 helicase, origin recognition complex, replication
• 由来する生物種: Saccharomyces cerevisiae S288c (Baker's yeast); 詳細
• タンパク質・核酸の鎖数: 14
• 化学式量合計: 1086942.90

構造登録者

Miller, T.C.R.,Locke, J.,Costa, A. (登録日: 2019-05-15, 公開日: 2019-11-20, 最終更新日: 2024-05-22)

主引用文献

Miller, T.C.R.,Locke, J.,Greiwe, J.F.,Diffley, J.F.X.,Costa, A.
Mechanism of head-to-head MCM double-hexamer formation revealed by cryo-EM.
Nature, 575:704-710, 2019

PubMed Abstract: In preparation for bidirectional DNA replication, the origin recognition complex (ORC) loads two hexameric MCM helicases to form a head-to-head double hexamer around DNA. The mechanism of MCM double-hexamer formation is debated. Single-molecule experiments have suggested a sequential mechanism, in which the ORC-dependent loading of the first hexamer drives the recruitment of the second hexamer. By contrast, biochemical data have shown that two rings are loaded independently via the same ORC-mediated mechanism, at two inverted DNA sites. Here we visualize MCM loading using time-resolved electron microscopy, and identify intermediates in the formation of the double hexamer. We confirm that both hexamers are recruited via the same interaction that occurs between ORC and the C-terminal domains of the MCM helicases. Moreover, we identify the mechanism of coupled MCM loading. The loading of the first MCM hexamer around DNA creates a distinct interaction site, which promotes the engagement of ORC at the N-terminal homodimerization interface of MCM. In this configuration, ORC is poised to direct the recruitment of the second hexamer in an inverted orientation, which is suitable for the formation of the double hexamer. Our results therefore reconcile the two apparently contrasting models derived from single-molecule experiments and biochemical data.

PubMed: 31748745
DOI: 10.1038/s41586-019-1768-0

実験手法

ELECTRON MICROSCOPY (4.4 Å)