Quadt R, Kao C C, Browning K S, Hershberger R P, Ahlquist P
Institute for Molecular Virology, University of Wisconsin-Madison 53706.
Proc Natl Acad Sci U S A. 1993 Feb 15;90(4):1498-502. doi: 10.1073/pnas.90.4.1498.
The association of host proteins with viral RNA replication proteins has been reported for a number of (+)-strand RNA viruses. However, little is known about the identity or function of these host proteins in viral replication. In this paper we report the characterization of a host protein associated with the RNA-dependent RNA polymerase (RdRp) from brome mosaic virus (BMV)-infected barley. A host protein was specifically and proportionally enriched with BMV RdRp activity through several purification steps. This RdRp-associated host protein reacted with an antiserum prepared against wheat germ eukaryotic translation initiation factor 3 (eIF-3). The RdRp-associated host protein, the p41 subunit of wheat germ eIF-3, and an antigenically related protein from rabbit reticulocyte lysates were all found to bind with high affinity and specificity to BMV-encoded protein 2a, which is involved in viral RNA replication. Moreover, addition of wheat germ eIF-3 or the p41 subunit from wheat germ to BMV RdRp gave a specific and reproducible 3-fold stimulation of (-)-strand RNA synthesis in vivo. These results suggest that the barley analog of eIF-3 subunit p41, or a closely related protein, associates with BMV RdRp in vivo and is involved in BMV RNA replication. This observation and the established role of translation factors in bacteriophage Q beta RdRp suggest that association with translation factors may be a general feature of RNA replication by (+)-strand RNA viruses.
已有报道称，多种正链RNA病毒存在宿主蛋白与病毒RNA复制蛋白的关联。然而，对于这些宿主蛋白在病毒复制中的身份或功能却知之甚少。在本文中，我们报道了一种与感染了雀麦花叶病毒（BMV）的大麦中依赖RNA的RNA聚合酶（RdRp）相关的宿主蛋白的特性。通过多个纯化步骤，一种宿主蛋白与BMV RdRp活性特异性地、成比例地富集。这种与RdRp相关的宿主蛋白能与针对小麦胚芽真核翻译起始因子3（eIF-3）制备的抗血清发生反应。发现与RdRp相关的宿主蛋白、小麦胚芽eIF-3的p41亚基以及兔网织红细胞裂解物中一种抗原相关蛋白均以高亲和力和特异性与BMV编码的参与病毒RNA复制的蛋白2a结合。此外，向BMV RdRp中添加小麦胚芽eIF-3或其p41亚基在体内对负链RNA合成产生了特异性且可重复的3倍刺激作用。这些结果表明，eIF-3亚基p41的大麦类似物或一种密切相关的蛋白在体内与BMV RdRp相关联，并参与BMV RNA复制。这一观察结果以及翻译因子在噬菌体Qβ RdRp中的既定作用表明，与翻译因子的关联可能是正链RNA病毒进行RNA复制的一个普遍特征。
