Transposases drive chromosomal rearrangements and the dissemination of drug-resistance genes and toxins^1,2,3. Although some transposases act alone, many rely on dedicated AAA+ ATPase subunits that regulate site selectivity and catalytic function through poorly understood mechanisms. Using IS21 as a model transposase system, we show how an ATPase regulator uses nucleotide-controlled assembly and DNA deformation to enable structure-based site selectivity, transposase recruitment, and activation and integration. Solution and cryogenic electron microscopy studies show that the IstB ATPase self-assembles into an autoinhibited pentamer of dimers that tightly curves target DNA into a half-coil. Two of these decamers dimerize, which stabilizes the target nucleic acid into a kinked S-shaped configuration that engages the IstA transposase at the interface between the two IstB oligomers to form an approximately 1 MDa transpososome complex. Specific interactions stimulate regulator ATPase activity and trigger a large conformational change on the transposase that positions the catalytic site to perform DNA strand transfer. These studies help explain how AAA+ ATPase regulators—which are used by classical transposition systems such as Tn7, Mu and CRISPR-associated elements—can remodel their substrate DNA and cognate transposases to promote function.

转座酶驱动染色体重排以及耐药基因和毒素的传播 ^1,2,3 。尽管一些转座酶单独起作用，但许多转座酶依赖于专用的 AAA+ ATP 酶亚基，通过知之甚少的机制调节位点选择性和催化功能。使用 IS21 作为模型转座酶系统，我们展示了 ATP 酶调节剂如何使用核苷酸控制的组装和 DNA 变形来实现基于结构的位点选择性、转座酶招募以及激活和整合。溶液和低温电子显微镜研究表明，IstB ATP 酶自组装成二聚体的自抑制五聚体，将目标 DNA 紧密地弯曲成半螺旋。其中两个十聚体二聚化，从而将靶核酸稳定成扭结的 S 形构型，该构型在两个 IstB 寡聚体之间的界面处与 IstA 转座酶接合，形成大约 1 MDa 的转座体复合物。特定的相互作用刺激调节剂 ATP 酶活性并引发转座酶的巨大构象变化，从而定位催化位点以进行 DNA 链转移。这些研究有助于解释 AAA+ ATP 酶调节因子（Tn7、Mu 和 CRISPR 相关元件等经典转座系统所使用）如何重塑其底物 DNA 和同源转座酶以促进功能。