Georgia State University, Department of Biology, Atlanta, GA 30303, USA.
Virology. 2010 Oct 25;406(2):212-27. doi: 10.1016/j.virol.2010.07.025. Epub 2010 Aug 8.
The P150 and P90 replicase proteins of rubella virus (RUBV), a plus-strand RNA Togavirus, produce a unique cytoplasmic fiber network resembling microtubules. Pharmacological and mutagenic approaches were used to determine if these fibers functioned in virus replication. The pharmacological approach revealed that microtubules were required for fiber formation, but neither was necessary for virus replication. Through the mutagenic approach it was found that α-helices near both termini of P150 were necessary for fiber assembly and infectivity, but fiber formation and viability could not be correlated because most of these mutations were lethal. The N-terminal α-helix of P150 affected both proteolytic processing of P150 and P90 from the P200 precursor and targeting of P200, possibly through directing conformational folding of P200. Finally, we made the unexpected discovery that RUBV genomes can spread from cell-to-cell without virus particles, a process that we hypothesize utilizes RUBV-induced cytoplasmic projections containing fibers and replication complexes.
风疹病毒（RUBV）的 P150 和 P90 复制酶蛋白是一种正链 RNA 披膜病毒，可产生类似于微管的独特细胞质纤维网络。我们采用药理学和诱变方法来确定这些纤维是否在病毒复制中发挥作用。药理学方法表明微管对于纤维的形成是必需的，但对于病毒的复制则不是必需的。通过诱变方法发现，P150 两端附近的α-螺旋对于纤维的组装和感染性是必需的，但纤维的形成和生存能力不能相关联，因为这些突变大多是致命的。P150 的 N 端α-螺旋影响 P150 和 P90 从 P200 前体的蛋白水解加工以及 P200 的靶向，可能通过指导 P200 的构象折叠来实现。最后，我们意外地发现，RUBV 基因组可以在没有病毒颗粒的情况下在细胞间传播，我们假设这一过程利用了 RUBV 诱导的包含纤维和复制复合物的细胞质突起。
