7MR0

Cryo-EM structure of RecBCD with docked RecBNuc and flexible RecD

7MR0 の概要

• エントリーDOI: 10.2210/pdb7mr0/pdb
• EMDBエントリー: 23952
• 分子名称: RecBCD enzyme subunit RecB, RecBCD enzyme subunit RecC, RecBCD enzyme subunit RecD (3 entities in total)
• 機能のキーワード: sf1 helicase, complex, dna repair, motor protein, hydrolase
• 由来する生物種: Escherichia coli K12; 詳細
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 330075.11

構造登録者

Hao, L.,Zhang, R.,Lohman, T.M. (登録日: 2021-05-07, 公開日: 2021-07-28, 最終更新日: 2025-05-14)

主引用文献

Hao, L.,Zhang, R.,Lohman, T.M.
Heterogeneity in E. coli RecBCD Helicase-DNA Binding and Base Pair Melting.
J.Mol.Biol., 433:167147-167147, 2021

PubMed Abstract: E. coli RecBCD, a helicase/nuclease involved in double stranded (ds) DNA break repair, binds to a dsDNA end and melts out several DNA base pairs (bp) using only its binding free energy. We examined RecBCD-DNA initiation complexes using thermodynamic and structural approaches. Measurements of enthalpy changes for RecBCD binding to DNA ends possessing pre-melted ssDNA tails of increasing length suggest that RecBCD interacts with ssDNA as long as 17-18 nucleotides and can melt at least 10-11 bp upon binding a blunt DNA end. Cryo-EM structures of RecBCD alone and in complex with a blunt-ended dsDNA show significant conformational heterogeneities associated with the RecB nuclease domain (RecB) and the RecD subunit. In the absence of DNA, 56% of RecBCD molecules show no density for the RecB nuclease domain, RecB, and all RecBCD molecules show only partial density for RecD. DNA binding reduces these conformational heterogeneities, with 63% of the molecules showing density for both RecD and RecB. This suggests that the RecB domain is dynamic and influenced by DNA binding. The major RecBCD-DNA structural class in which RecB is docked onto RecC shows melting of at least 11 bp from a blunt DNA end, much larger than previously observed. A second structural class in which RecB is not docked shows only four bp melted suggesting that RecBCD complexes transition between states with different extents of DNA melting and that the extent of melting regulates initiation of helicase activity.

PubMed: 34246654
DOI: 10.1016/j.jmb.2021.167147

実験手法

ELECTRON MICROSCOPY (3.7 Å)