Boerner Joanna E, Lyle John M, Daijogo Sarah, Semler Bert L, Schultz Stephen C, Kirkegaard Karla, Richards Oliver C
Stanford University School of Medicine, Department of Microbiology and Immunology, Fairchild Science Building D309A, Stanford, CA 94305-5402, USA.
J Virol. 2005 Jun;79(12):7803-11. doi: 10.1128/JVI.79.12.7803-7811.2005.
Protein priming of viral RNA synthesis plays an essential role in the replication of picornavirus RNA. Both poliovirus and coxsackievirus encode a small polypeptide, VPg, which serves as a primer for addition of the first nucleotide during synthesis of both positive and negative strands. This study examined the effects on the VPg uridylylation reaction of the RNA template sequence, the origin of VPg (coxsackievirus or poliovirus), the origin of 3D polymerase (coxsackievirus or poliovirus), the presence and origin of interacting protein 3CD, and the introduction of mutations at specific regions in the poliovirus 3D polymerase. Substantial effects associated with VPg origin were traced to differences in VPg-polymerase interactions. The effects of 3CD proteins and mutations at polymerase-polymerase intermolecular Interface I were most consistent with allosteric effects on the catalytic 3D polymerase molecule. In conclusion, the efficiency and specificity of VPg uridylylation by picornavirus polymerases is greatly influenced by allosteric effects of ligand binding that are likely to be relevant during the viral replicative cycle.
病毒RNA合成的蛋白质引发在小核糖核酸病毒RNA的复制中起着至关重要的作用。脊髓灰质炎病毒和柯萨奇病毒都编码一种小多肽，即病毒蛋白质基因组连接蛋白（VPg），它在正链和负链合成过程中作为添加第一个核苷酸的引物。本研究考察了RNA模板序列、VPg的来源（柯萨奇病毒或脊髓灰质炎病毒）、3D聚合酶的来源（柯萨奇病毒或脊髓灰质炎病毒）、相互作用蛋白3CD的存在及其来源，以及脊髓灰质炎病毒3D聚合酶特定区域突变的引入对VPg尿苷酸化反应的影响。与VPg来源相关的显著影响可追溯到VPg-聚合酶相互作用的差异。3CD蛋白的影响以及聚合酶-聚合酶分子间界面I处的突变最符合对催化性3D聚合酶分子的变构效应。总之，小核糖核酸病毒聚合酶对VPg尿苷酸化的效率和特异性受到配体结合变构效应的极大影响，这些效应可能在病毒复制周期中起作用。
