Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 912, Taiwan.
Virus Res. 2010 Apr;149(1):71-7. doi: 10.1016/j.virusres.2010.01.003. Epub 2010 Jan 15.
By Western blot analyzes of expression of avian reovirus proteins, one unknown fragment was detected by an anti-sigmaA monoclonal antibody in virus-infected cells lysate. It was interesting to note that RNA interference against sigmaA resulted in the suppression of the unknown fragment. Using various lengths of sigmaA constructs conjugated with different tags, we present evidences to demonstrate that the fragment comes from the cleavage of sigmaA and is the larger carboxyl-terminus, termed sigmaAC. Cleavage of sigmaA simultaneously produces a smaller amino-terminus, named sigmaAN. sigmaAC could be seen early in viral infection and accumulated with time and dose of infection, indicating that the derived products are not just transient intermediates of protein degradation. The same type of cleaved products were also observed in different genotypes and serotypes of ARV as well as in different cell lines, suggesting that this intracellular modification of sigmaA is common to all ARVs. Similar localization of sigmaAC in both cytosol and nucleus with sigmaA suggested that further modification of sigmaA may be important for its function. Our evidences suggest that besides the outer capsid protein muB, sigmaA may also have post-translational cleavage which has never been reported before even in related mammalian reovirus.
通过对禽呼肠孤病毒蛋白表达的 Western blot 分析，在病毒感染细胞裂解物中，抗 sigmaA 单克隆抗体检测到一个未知片段。有趣的是，针对 sigmaA 的 RNA 干扰导致该未知片段被抑制。使用与不同标签偶联的各种长度的 sigmaA 构建体，我们提供了证据证明该片段来自 sigmaA 的切割，是更大的羧基末端，称为 sigmaAC。sigmaA 的切割同时产生较小的氨基末端，命名为 sigmaAN。sigmaAC 可在病毒感染早期看到，并随感染时间和剂量的增加而积累，表明衍生产物不仅是蛋白降解的短暂中间体。在不同基因型和血清型的 ARV 以及不同的细胞系中也观察到了相同类型的切割产物，表明 sigmaA 的这种细胞内修饰在所有 ARV 中都是常见的。sigmaAC 与 sigmaA 在细胞质和核内的相似定位表明，sigmaA 的进一步修饰可能对其功能很重要。我们的证据表明，除了外壳蛋白 muB 之外，sigmaA 可能还具有以前从未报道过的翻译后切割，甚至在相关的哺乳动物呼肠孤病毒中也没有报道过。
