西班牙玛格丽塔·萨拉斯生物研究中心Ernesto Arias-Palomo等研究人员，合作揭示了专用AAA+ ATP酶激活转座酶的分子基础。该研究于2024年6月26日在线发表于国际一流学术期刊《自然》。

研究人员以IS21为转座酶系统模型，展示了ATP酶调节器如何利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酶能自我组装成一个由二聚体组成的自动抑制五聚体，将目标DNA紧紧卷成一个半线圈。其中两个十聚体发生二聚化，从而将目标核酸稳定为扭结的S形构型，使IstA转座酶在两个IstB寡聚体之间的界面上接合，形成约1 MDa的转座复合体。

特定的相互作用会刺激调节器ATP酶的活性，并引发转座酶发生巨大的构象变化，从而使催化位点就位，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使用的调节因子），如何重塑其底物DNA和同源转座酶以促进功能。

据了解，转座酶驱动染色体重排，并传播耐药基因和毒素。虽然有些转座酶是单独起作用的，但许多转座酶依赖于专用的 AAA+ ATP酶亚基，这些亚基通过不甚明了的机制调节位点选择性和催化功能。

附：英文原文

Title: Molecular basis for transposase activation by a dedicated AAA+ ATPase

Author: de la Gndara, lvaro, Spnola-Amilibia, Mercedes, Arajo-Bazn, Lidia, Nez-Ramrez, Rafael, Berger, James M., Arias-Palomo, Ernesto

Issue&Volume: 2024-06-26

Abstract: Transposases drive chromosomal rearrangements and the dissemination of drug-resistance genes and toxins1,2,3. 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 1MDa 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.

DOI: 10.1038/s41586-024-07550-6

Source: https://www.nature.com/articles/s41586-024-07550-6