Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Viruses. 2022 Oct 8;14(10):2215. doi: 10.3390/v14102215.
The genome packaging motor of bacteriophages and herpesviruses is built by two terminase subunits, known as large (TerL) and small (TerS), both essential for viral genome packaging. TerL structure, composition, and assembly to an empty capsid, as well as the mechanisms of ATP-dependent DNA packaging, have been studied in depth, shedding light on the chemo-mechanical coupling between ATP hydrolysis and DNA translocation. Instead, significantly less is known about the small terminase subunit, TerS, which is dispensable or even inhibitory in vitro, but essential in vivo. By taking advantage of the recent revolution in cryo-electron microscopy (cryo-EM) and building upon a wealth of crystallographic structures of phage TerSs, in this review, we take an inventory of known TerSs studied to date. Our analysis suggests that TerS evolved and diversified into a flexible molecular framework that can conserve biological function with minimal sequence and quaternary structure conservation to fit different packaging strategies and environmental conditions.
噬菌体和疱疹病毒的基因组包装马达由两个末端酶亚基组成，分别称为大（TerL）和小（TerS），它们都是病毒基因组包装所必需的。TerL 的结构、组成和空衣壳的组装，以及 ATP 依赖性 DNA 包装的机制，已经得到了深入研究，揭示了 ATP 水解和 DNA 转位之间的化学机械偶联。相比之下，关于小末端酶亚基 TerS 的了解要少得多，TerS 在体外是可有可无的，甚至是抑制性的，但在体内却是必需的。本综述利用最近 cryo-electron microscopy (cryo-EM) 的革命成果，并基于大量噬菌体 TerSs 的晶体结构，对迄今为止研究过的已知 TerSs 进行了盘点。我们的分析表明，TerS 进化并多样化为一个灵活的分子框架，可以在最小的序列和四级结构保守的情况下保留生物功能，以适应不同的包装策略和环境条件。
