上海士锋生物关于解旋酶结构域助酶漫步DNA的研究

解旋酶（Helicase）是一类分布广泛的三磷酸腺苷酶（ATP酶, ATPase），在基因组代谢中具起着广泛的作用。这项研究报道了一个先前研究中被忽视的带有解旋酶类似结构域的ATP酶的功能，也就是说，ATP水解可以激活ATP依赖的长距离的蛋白质在DNA上的一维扩散。特别的是，使用单分子荧光显微镜观察，可以看到III类限制性内切酶EcoP15I可以使用它的ATP水解酶来将自身转变成一个不同结构的状态，然后使其在DNA上长时间长距离地扩散。这个转化只在结合到特定的靶位点时候发生，且需要消耗约30个ATP分子。研究人员确定了这些酶的机制并展示了ATP酶活动如何参与DNA靶位点确认和一维信号传导，从而参与如核苷酸切除修复和错配修复等DNA常见的代谢过程。

The Helicase-Like Domains of Type III Restriction Enzymes Trigger Long-Range Diffusion Along DNA

Friedrich W. Schwarz, Júlia Tóth, Kara van Aelst, Guanshen Cui, Sylvia Clausing, Mark D. Szczelkun, Ralf Seidel

Helicases are ubiquitous adenosine triphosphatases （ATPases） with widespread roles in genome metabolism. Here, we report a previously undescribed functionality for ATPases with helicase-like domains; namely, that ATP hydrolysis can trigger ATP-independent long-range protein diffusion on DNA in one dimension （1D）. Specifically, using single-molecule fluorescence microscopy we show that the Type III restriction enzyme EcoP15I uses its ATPase to switch into a distinct structural state that diffuses on DNA over long distances and long times. The switching occurs only upon binding to the target site and requires hydrolysis of ~30 ATPs. We define the mechanism for these enzymes and show how ATPase activity is involved in DNA target site verification and 1D signaling, roles that are common in DNA metabolism: for example, in nucleotide excision and mismatch repair.