5BK4

Cryo-EM structure of Mcm2-7 double hexamer on dsDNA

5BK4 の概要

• エントリーDOI: 10.2210/pdb5bk4/pdb
• EMDBエントリー: 9400
• 分子名称: DNA replication licensing factor MCM2, DNA replication licensing factor MCM3, DNA replication licensing factor MCM4, ... (9 entities in total)
• 機能のキーワード: complex, dna replication, hydrolase-dna complex, hydrolase/dna
• 由来する生物種: Saccharomyces cerevisiae (Baker's yeast); 詳細
• タンパク質・核酸の鎖数: 14
• 化学式量合計: 1253139.79

構造登録者

Li, H.,Yuan, Z.,Bai, L. (登録日: 2017-09-12, 公開日: 2017-10-25, 最終更新日: 2024-10-16)

主引用文献

Noguchi, Y.,Yuan, Z.,Bai, L.,Schneider, S.,Zhao, G.,Stillman, B.,Speck, C.,Li, H.
Cryo-EM structure of Mcm2-7 double hexamer on DNA suggests a lagging-strand DNA extrusion model.
Proc. Natl. Acad. Sci. U.S.A., 114:E9529-E9538, 2017

PubMed Abstract: During replication initiation, the core component of the helicase-the Mcm2-7 hexamer-is loaded on origin DNA as a double hexamer (DH). The two ring-shaped hexamers are staggered, leading to a kinked axial channel. How the origin DNA interacts with the axial channel is not understood, but the interaction could provide key insights into Mcm2-7 function and regulation. Here, we report the cryo-EM structure of the Mcm2-7 DH on dsDNA and show that the DNA is zigzagged inside the central channel. Several of the Mcm subunit DNA-binding loops, such as the oligosaccharide-oligonucleotide loops, helix 2 insertion loops, and presensor 1 (PS1) loops, are well defined, and many of them interact extensively with the DNA. The PS1 loops of Mcm 3, 4, 6, and 7, but not 2 and 5, engage the lagging strand with an approximate step size of one base per subunit. Staggered coupling of the two opposing hexamers positions the DNA right in front of the two Mcm2-Mcm5 gates, with each strand being pressed against one gate. The architecture suggests that lagging-strand extrusion initiates in the middle of the DH that is composed of the zinc finger domains of both hexamers. To convert the Mcm2-7 DH structure into the Mcm2-7 hexamer structure found in the active helicase, the N-tier ring of the Mcm2-7 hexamer in the DH-dsDNA needs to tilt and shift laterally. We suggest that these N-tier ring movements cause the DNA strand separation and lagging-strand extrusion.

PubMed: 29078375
DOI: 10.1073/pnas.1712537114

実験手法

ELECTRON MICROSCOPY (3.9 Å)