Bioelectronics, The Pollard Institute, School of Electronic and Electrical Engineering, University of Leeds, Woodhouse lane, Leeds LS2 9JT, UK.
Institute for Integrated Cell-Material Sciences, Kyoto University, Yoshida-ushinomiyacho, Sakyo-ku, Kyoto 606-8501, Japan.
Nucleic Acids Res. 2021 Feb 22;49(3):1426-1435. doi: 10.1093/nar/gkaa1258.
Recombinase A (RecA) is central to homologous recombination. However, despite significant advances, the mechanism with which RecA is able to orchestrate a search for homology remains elusive. DNA nanostructure-augmented high-speed AFM offers the spatial and temporal resolutions required to study the RecA recombination mechanism directly and at the single molecule level. We present the direct in situ observation of RecA-orchestrated alignment of homologous DNA strands to form a stable recombination product within a supporting DNA nanostructure. We show the existence of subtle and short-lived states in the interaction landscape, which suggests that RecA transiently samples micro-homology at the single RecA monomer-level throughout the search for sequence alignment. These transient interactions form the early steps in the search for sequence homology, prior to the formation of stable pairings at >8 nucleotide seeds. The removal of sequence micro-homology results in the loss of the associated transient sampling at that location.
RecA（重组酶 A）是同源重组的核心。然而，尽管已经取得了重大进展，但 RecA 能够协调同源搜索的机制仍然难以捉摸。DNA 纳米结构增强的高速 AFM 提供了研究 RecA 重组机制所需的空间和时间分辨率，可以直接在单分子水平上进行研究。我们展示了在支持 DNA 纳米结构内直接原位观察 RecA 协调排列同源 DNA 链以形成稳定重组产物的过程。我们发现了相互作用景观中的微妙和短暂存在的状态，这表明 RecA 在整个序列比对搜索过程中，在单个 RecA 单体水平上短暂地探测微同源性。这些短暂的相互作用形成了序列同源性搜索的早期步骤，在形成 >8 个核苷酸种子的稳定配对之前。序列微同源性的去除导致该位置相关的短暂采样丢失。
