7JY6

Analysis of a strand exchange reaction with a mini filament of 9-RecA, oligo(dT)27 primary ssDNA, non-homologous 120 bp dsDNA and ATPgammaS

7JY6 の概要

• エントリーDOI: 10.2210/pdb7jy6/pdb
• EMDBエントリー: 22522
• 分子名称: Protein RecA, DNA (27-MER), DNA (45-MER), ... (5 entities in total)
• 機能のキーワード: recombination, dna repair, dna binding protein, dna binding protein-dna complex, dna binding protein/dna
• 由来する生物種: Escherichia coli; 詳細
• タンパク質・核酸の鎖数: 11
• 化学式量合計: 350382.46

構造登録者

Pavletich, N.P. (登録日: 2020-08-29, 公開日: 2020-11-04, 最終更新日: 2024-03-06)

主引用文献

Yang, H.,Zhou, C.,Dhar, A.,Pavletich, N.P.
Mechanism of strand exchange from RecA-DNA synaptic and D-loop structures.
Nature, 586:801-806, 2020

PubMed Abstract: The strand-exchange reaction is central to homologous recombination. It is catalysed by the RecA family of ATPases, which form a helical filament with single-stranded DNA (ssDNA) and ATP. This filament binds to a donor double-stranded DNA (dsDNA) to form synaptic filaments, which search for homology and then catalyse the exchange of the complementary strand, forming either a new heteroduplex or-if homology is limited-a D-loop. How synaptic filaments form, search for homology and catalyse strand exchange is poorly understood. Here we report the cryo-electron microscopy analysis of synaptic mini-filaments with both non-complementary and partially complementary dsDNA, and structures of RecA-D-loop complexes containing a 10- or a 12-base-pair heteroduplex. The C-terminal domain of RecA binds to dsDNA and directs it to the RecA L2 loop, which inserts into and opens up the duplex. The opening propagates through RecA sequestering the homologous strand at a secondary DNA-binding site, which frees the complementary strand to sample pairing with the ssDNA. At each RecA step, there is a roughly 20% probability that duplex opening will terminate and the as-yet-unopened dsDNA portion will bind to another C-terminal domain. Homology suppresses this process, through the cooperation of heteroduplex pairing with the binding of ssDNA to the secondary site, to extend dsDNA opening. This mechanism locally limits the length of ssDNA sampled for pairing if homology is not encountered, and could allow for the formation of multiple, widely separated synapses on the donor dsDNA, which would increase the likelihood of encountering homology. These findings provide key mechanistic insights into homologous recombination.

PubMed: 33057191
DOI: 10.1038/s41586-020-2820-9

実験手法

ELECTRON MICROSCOPY (2.5 Å)