7W7P

Cryo-EM structure of gMCM8/9 helicase

Summary for 7W7P

• Entry DOI: 10.2210/pdb7w7p/pdb
• EMDB information: 32346
• Descriptor: DNA helicase MCM9, DNA helicase MCM8 (2 entities in total)
• Functional Keywords: mcm8/9, hydrolase
• Biological source: Gallus gallus (chicken); More
• Total number of polymer chains: 6
• Total formula weight: 196467.31

Authors

Zheng, J.F.,Weng, Z.F.,Liu, Y.F. (deposition date: 2021-12-06, release date: 2023-05-24, Last modification date: 2023-12-06)

Primary citation

Weng, Z.,Zheng, J.,Zhou, Y.,Lu, Z.,Wu, Y.,Xu, D.,Li, H.,Liang, H.,Liu, Y.
Structural and mechanistic insights into the MCM8/9 helicase complex.
Elife, 12:-, 2023

PubMed Abstract: MCM8 and MCM9 form a functional helicase complex (MCM8/9) that plays an essential role in DNA homologous recombination repair for DNA double-strand break. However, the structural characterization of MCM8/9 for DNA binding/unwinding remains unclear. Here, we report structures of the MCM8/9 complex using cryo-electron microscopy single particle analysis. The structures reveal that MCM8/9 is arranged into a heterohexamer through a threefold symmetry axis, creating a central channel that accommodates DNA. Multiple characteristic hairpins from the N-terminal oligosaccharide/oligonucleotide (OB) domains of MCM8/9 protrude into the central channel and serve to unwind the duplex DNA. When activated by HROB, the structure of MCM8/9's N-tier ring converts its symmetry from to with a conformational change that expands the MCM8/9's trimer interface. Moreover, our structural dynamic analyses revealed that the flexible C-tier ring exhibited rotary motions relative to the N-tier ring, which is required for the unwinding ability of MCM8/9. In summary, our structural and biochemistry study provides a basis for understanding the DNA unwinding mechanism of MCM8/9 helicase in homologous recombination.

PubMed: 37535404
DOI: 10.7554/eLife.87468

Experimental method

ELECTRON MICROSCOPY (3.67 Å)