Some DNA helicases play central and specific roles in genome maintenance and plasticity through their branch migration activity in different pathways of homologous recombination. RadA is a highly conserved bacterial helicase involved in DNA repair throughout all bacterial species. In Gram-positive Firmicutes, it also has a role in natural transformation, while in Gram-negative bacteria, ComM is the canonical transformation-specific helicase. Both RadA and ComM helicases form hexameric rings and use ATP hydrolysis as an energy source to propel themselves along DNA. In this study, we present the cryoEM structures of RadA and ComM interacting with DNA and ATP analogs. These structures reveal important molecular interactions that couple ATP hydrolysis and DNA binding in RadA, as well as the role of the Lon protease-like domain, shared by RadA and ComM, in this process. Taken together, these results provide new molecular insights into the mechanisms of DNA branch migration in different pathways of homologous recombination.

中文翻译：

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对细菌同源重组过程中 DNA 分支迁移机制的结构见解。


一些 DNA 解旋酶通过其在同源重组的不同途径中的分支迁移活性，在基因组维持和可塑性中发挥核心和特异性作用。RadA 是一种高度保守的细菌解旋酶，参与所有细菌种类的 DNA 修复。在革兰氏阳性厚壁菌门中，它也具有自然转化的作用，而在革兰氏阴性菌中，ComM 是经典的转化特异性解旋酶。RadA 和 ComM 解旋酶都形成六聚体环，并使用 ATP 水解作为能量来源来推动自身沿着 DNA 移动。在这项研究中，我们提出了 RadA 和 ComM 的 cryoEM 结构与 DNA 和 ATP 类似物相互作用。这些结构揭示了 RadA 中偶联 ATP 水解和 DNA 结合的重要分子相互作用，以及 RadA 和 ComM 共享的 Lon 蛋白酶样结构域在此过程中的作用。综上所述，这些结果为不同同源重组途径中 DNA 分支迁移的机制提供了新的分子见解。