Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
Proc Natl Acad Sci U S A. 2013 May 14;110(20):8075-80. doi: 10.1073/pnas.1301133110. Epub 2013 Apr 29.
Many DNA viruses use powerful molecular motors to cleave concatemeric viral DNA into genome-length units and package them into preformed procapsid powered by ATP hydrolysis. Here we report the structures of the DNA-packaging motor gp2 of bacteriophage Sf6, which reveal a unique clade of RecA-like ATPase domain and an RNase H-like nuclease domain tethered by a regulatory linker domain, exhibiting a strikingly distinct domain arrangement. The gp2 structures complexed with nucleotides reveal, at the atomic detail, the catalytic center embraced by the ATPase domain and the linker domain. The gp2 nuclease activity is modulated by the ATPase domain and is stimulated by ATP. An extended DNA-binding surface is formed by the linker domain and the nuclease domain. These results suggest a unique mechanism for translation of chemical reaction into physical motion of DNA and provide insights into coordination of DNA translocation and cleavage in a viral DNA-packaging motor, which may be achieved via linker-domain-mediated interdomain communication driven by ATP hydrolysis.
许多 DNA 病毒利用强大的分子马达将连接的病毒 DNA 切割成基因组长度的单位，并将其包装到由 ATP 水解驱动的预制衣壳中。在这里，我们报告了 Sf6 噬菌体的 DNA 包装马达 gp2 的结构，它揭示了一个独特的 RecA 样 ATP 酶结构域和一个 RNase H 样核酸酶结构域的分支，由一个调节连接子结构域连接，表现出截然不同的结构域排列。与核苷酸复合的 gp2 结构以原子细节揭示了 ATP 酶结构域和连接子结构域所包围的催化中心。gp2 核酸酶活性受 ATP 酶结构域调节，并受 ATP 刺激。连接子结构域和核酸酶结构域形成了一个扩展的 DNA 结合表面。这些结果表明了一种将化学反应转化为 DNA 物理运动的独特机制，并为病毒 DNA 包装马达中 DNA 易位和切割的协调提供了见解，这可能是通过由 ATP 水解驱动的连接子结构域介导的结构域间通信来实现的。
