Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK.
Nucleic Acids Res. 2023 Feb 22;51(3):1001-1018. doi: 10.1093/nar/gkac733.
Site-specific DNA recombinases play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful synthetic biology tools. The simplest site-specific recombination systems will recombine any two cognate sites regardless of context. Other systems have evolved elaborate mechanisms, often sensing DNA topology, to ensure that only one of multiple possible recombination products is produced. The closely related resolvases from the Tn3 and γδ transposons have historically served as paradigms for the regulation of recombinase activity by DNA topology. However, despite many proposals, models of the multi-subunit protein-DNA complex (termed the synaptosome) that enforces this regulation have been unsatisfying due to a lack of experimental constraints and incomplete concordance with experimental data. Here, we present new structural and biochemical data that lead to a new, detailed model of the Tn3 synaptosome, and discuss how it harnesses DNA topology to regulate the enzymatic activity of the recombinase.
位点特异性 DNA 重组酶在多种生物学过程中发挥作用，通常与抗生素耐药性的传播有关，同时也是有用的合成生物学工具。最简单的位点特异性重组系统可以在不考虑上下文的情况下重组任何两个同源位点。其他系统已经进化出了复杂的机制，通常通过感知 DNA 拓扑结构来确保只产生多个可能的重组产物之一。来自 Tn3 和 γδ 转座子的密切相关的 resolvases 一直以来都是通过 DNA 拓扑结构调节重组酶活性的典范。然而，尽管有许多提议，但由于缺乏实验约束和与实验数据不完全一致，多亚基蛋白-DNA 复合物（称为 synaptosome）的模型一直无法令人满意。在这里，我们提出了新的结构和生化数据，这些数据导致了 Tn3 synaptosome 的新的、详细的模型，并讨论了它如何利用 DNA 拓扑结构来调节重组酶的酶活性。
