Ypma-Wong M F, Dewalt P G, Johnson V H, Lamb J G, Semler B L
Department of Microbiology and Molecular Genetics, California College of Medicine, University of California, Irvine 92717.
Virology. 1988 Sep;166(1):265-70. doi: 10.1016/0042-6822(88)90172-9.
The rate and extent of polyprotein processing are the major steps controlling picornavirus gene expression. It is, therefore, important to determine the enzymes responsible for each proteolytic event. The poliovirus protein 3C has been identified as a proteinase which specifically cleaves between Q-G pairs. However, recent data have suggested that 3C precursor polypeptides containing 3C sequences may also have proteolytic capabilities. In this study we have analyzed the cleavage specificities of protein 3C and its precursor, 3CD. We have carried out in vitro translation of genetically altered poliovirus mRNAs to demonstrate that 3CD is required for efficient processing of the P1 capsid precursor to capsid proteins. In addition, we suggest 3CD and 3C process Q-G pairs in the P2 and P3 precursors with similar efficiencies.
多聚蛋白加工的速率和程度是控制小RNA病毒基因表达的主要步骤。因此，确定负责每个蛋白水解事件的酶很重要。脊髓灰质炎病毒蛋白3C已被鉴定为一种蛋白酶，它特异性地在Q-G对之间切割。然而，最近的数据表明，含有3C序列的3C前体多肽也可能具有蛋白水解能力。在本研究中，我们分析了蛋白3C及其前体3CD的切割特异性。我们对基因改造的脊髓灰质炎病毒mRNA进行了体外翻译，以证明3CD是P1衣壳前体有效加工成衣壳蛋白所必需的。此外，我们认为3CD和3C以相似的效率加工P2和P3前体中的Q-G对。
