Schmutz C, Rindisbacher L, Galmiche M C, Wittek R
Institut de Biologie Animale, Université de Lausanne, Switzerland.
Virology. 1995 Oct 20;213(1):19-27. doi: 10.1006/viro.1995.1542.
The major envelope antigen of vaccinia virus is an acylated protein of M(r) 37,000 (p37K) which is required for the formation of extracellular enveloped virions (EEV). Despite its important role in the wrapping process, p37K has not been studied in much detail. In order to better characterize this protein we have undertaken a detailed biochemical analysis. Sodium carbonate treatment showed that p37K is tightly bound to the viral envelope. Its resistance to proteinase K digestion indicates that it is not exposed on the surface of EEV but lines the inner side of the envelope. Since p37K does not contain a signal peptide characteristic of most membrane proteins, we examined the possibility that the protein acquires its membrane affinity through the addition of fatty acids. Indeed, Triton X-114 phase partitioning experiments demonstrated that p37K is hydrophobic when acylated, but hydrophilic in the absence of fatty acids. Three other viral proteins have been shown to be required for virus envelopment and release from the host cell and we therefore tested whether p37K interacts with viral proteins. In EEV and in absence of reducing agents, an 80-kDa complex reacting with an anti-37K antiserum was found. Analysis of this complex showed that it most likely consists of a p37K homodimer. Interestingly, only a small amount of p37K occurs as a complex, most of it is present in the viral envelope as monomers.
痘苗病毒的主要包膜抗原是一种分子量为37,000的酰化蛋白（p37K），它是细胞外被膜病毒粒子（EEV）形成所必需的。尽管p37K在包膜过程中起重要作用，但对其研究并不详细。为了更好地表征这种蛋白质，我们进行了详细的生化分析。碳酸钠处理表明p37K与病毒包膜紧密结合。它对蛋白酶K消化的抗性表明它不暴露于EEV表面，而是排列在包膜内侧。由于p37K不包含大多数膜蛋白特有的信号肽，我们研究了该蛋白通过添加脂肪酸获得膜亲和力的可能性。实际上，Triton X-114相分配实验表明，酰化时p37K是疏水的，但在没有脂肪酸的情况下是亲水的。另外三种病毒蛋白已被证明是病毒包膜形成和从宿主细胞释放所必需的，因此我们测试了p37K是否与病毒蛋白相互作用。在EEV中且不存在还原剂的情况下，发现了一种与抗37K抗血清反应的80 kDa复合物。对该复合物的分析表明，它很可能由p37K同二聚体组成。有趣的是，只有少量p37K以复合物形式存在，大部分以单体形式存在于病毒包膜中。
