Mirzakhanyan Yeva, Gershon Paul D
Department of Molecular Biology & Biochemisty, University of California-Irvine, Irvine, California, USA.
Department of Molecular Biology & Biochemisty, University of California-Irvine, Irvine, California, USA
Microbiol Mol Biol Rev. 2017 Jul 12;81(3). doi: 10.1128/MMBR.00010-17. Print 2017 Sep.
The past 17 years have been marked by a revolution in our understanding of cellular multisubunit DNA-dependent RNA polymerases (MSDDRPs) at the structural level. A parallel development over the past 15 years has been the emerging story of the giant viruses, which encode MSDDRPs. Here we link the two in an attempt to understand the specialization of multisubunit RNA polymerases in the domain of life encompassing the large nucleocytoplasmic DNA viruses (NCLDV), a superclade that includes the giant viruses and the biochemically well-characterized poxvirus vaccinia virus. The first half of this review surveys the recently determined structural biology of cellular RNA polymerases for a microbiology readership. The second half discusses a reannotation of MSDDRP subunits from NCLDV families and the apparent specialization of these enzymes by virus family and by subunit with regard to subunit or domain loss, subunit dissociability, endogenous control of polymerase arrest, and the elimination/customization of regulatory interactions that would confer higher-order cellular control. Some themes are apparent in linking subunit function to structure in the viral world: as with cellular RNA polymerases I and III and unlike cellular RNA polymerase II, the viral enzymes seem to opt for speed and processivity and seem to have eliminated domains associated with higher-order regulation. The adoption/loss of viral RNA polymerase proofreading functions may have played a part in matching intrinsic mutability to genome size.
在过去的17年里，我们对细胞多亚基DNA依赖性RNA聚合酶（MSDDRPs）的结构理解发生了一场革命。在过去的15年里，一个与之并行发展的故事是巨型病毒的出现，它们编码MSDDRPs。在这里，我们将两者联系起来，试图了解在包括大型核质DNA病毒（NCLDV）的生命领域中多亚基RNA聚合酶的特化，NCLDV是一个超类群，包括巨型病毒和生物化学特征明确的痘病毒——痘苗病毒。本综述的前半部分为微生物学读者概述了细胞RNA聚合酶最近确定的结构生物学。后半部分讨论了对NCLDV家族MSDDRP亚基的重新注释，以及这些酶在病毒家族和亚基方面在亚基或结构域丢失、亚基解离性、聚合酶停滞的内源性控制以及消除/定制赋予更高阶细胞控制的调节相互作用方面的明显特化。在将病毒世界中的亚基功能与结构联系起来时，一些主题显而易见：与细胞RNA聚合酶I和III一样，但与细胞RNA聚合酶II不同，病毒酶似乎选择了速度和持续性，并且似乎已经消除了与高阶调节相关的结构域。病毒RNA聚合酶校对功能的采用/丧失可能在使内在突变性与基因组大小相匹配方面发挥了作用。
