Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA.
Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, USA.
Sci Rep. 2017 Aug 8;7(1):7582. doi: 10.1038/s41598-017-07997-w.
Studies on dsDNA bacteriophages have revealed that a DNA packaging complex assembles at a special vertex called the 'portal vertex' and consists of a portal, a DNA packaging ATPase and other components. AdV protein IVa2 is presumed to function as a DNA packaging ATPase. However, a protein that functions as a portal is not yet identified in AdVs. To identify the AdV portal, we performed secondary structure analysis on a set of AdV proteins and compared them with the clip region of the portal proteins of bacteriophages phi29, SPP1 and T4. Our analysis revealed that the E4 34K protein of HAdV-C5 contains a region of strong similarity with the clip region of the known portal proteins. E4 34K was found to be present in empty as well as mature AdV particles. In addition, E4 34K co-immunoprecipitates and colocalizes with AdV packaging proteins. Immunogold electron microscopy demonstrated that E4 34K is located at a single site on the virus surface. Finally, tertiary structure prediction of E4 34K and its comparison with that of single subunits of Phi29, SPP1 and T4 portal proteins revealed remarkable similarity. In conclusion, our results suggest that E4 34K is the putative AdV portal protein.
对双链 DNA 噬菌体的研究表明，一个 DNA 包装复合物在一个称为“门户顶点”的特殊顶点组装，由一个门户、一个 DNA 包装 ATP 酶和其他组件组成。AdV 蛋白 IVa2 被认为是 DNA 包装 ATP 酶的功能。然而，AdV 中尚未鉴定出具有门户功能的蛋白质。为了鉴定 AdV 门户，我们对一组 AdV 蛋白进行了二级结构分析，并将其与噬菌体 phi29、SPP1 和 T4 的门户蛋白的夹区进行了比较。我们的分析表明，HAdV-C5 的 E4 34K 蛋白含有与已知门户蛋白的夹区具有强烈相似性的区域。E4 34K 存在于空病毒粒子和成熟的 AdV 粒子中。此外，E4 34K 与 AdV 包装蛋白共同免疫沉淀和共定位。免疫金电子显微镜显示，E4 34K 位于病毒表面的一个单一位置。最后，E4 34K 的三级结构预测及其与 Phi29、SPP1 和 T4 门户蛋白的单个亚基的比较显示出显著的相似性。总之，我们的结果表明，E4 34K 是假定的 AdV 门户蛋白。
