Elliott G, O'Reilly D, O'Hare P
Marie Curie Research Institute, The Chart, Oxteo, Surrey, United Kingdom.
Virology. 1996 Dec 1;226(1):140-5. doi: 10.1006/viro.1996.0638.
The herpes simplex virus type 1 tegument protein VP22 is known to be highly phosphorylated during infection. Here we show that two electrophoretic forms of VP22 can be identified in infected cell extracts and that this heterogeneity is accounted for by phosphorylation. Furthermore, the nonphosphorylated form of VP22 appears to be specifically incorporated into virions. We also show that the phosphorylated form of VP22 is the only form detected during transient transfection and as such that VP22 can act as a substrate for a cellular kinase. Phospho-amino acid and phospho-peptide analyses of in vivo labeled VP22 were utilized to demonstrate that the phosphorylation profiles of VP22 synthesized during transfection and infection are the same. In both cases VP22 was modified solely on serine residues located in the N-terminal 120 residues of the protein. Moreover, in vitro phosphorylation was utilized to show that the constitutive cellular kinase, casein kinase II, which has four serine consensus recognition sites at the N-terminus of VP22, phosphorylates VP22 in the same manner as observed in vivo. This kinase also phosphorylates VP22 at the N-terminus in intact capsid-tegument structures. Casein kinase II is therefore likely to be the major kinase of VP22 during infection.
已知单纯疱疹病毒1型（HSV-1）的被膜蛋白VP22在感染过程中会发生高度磷酸化。在此我们表明，在感染细胞提取物中可鉴定出VP22的两种电泳形式，这种异质性是由磷酸化引起的。此外，VP22的非磷酸化形式似乎特异性地整合到病毒颗粒中。我们还表明，VP22的磷酸化形式是瞬时转染过程中检测到的唯一形式，因此VP22可作为细胞激酶的底物。利用体内标记的VP22进行的磷酸氨基酸和磷酸肽分析表明，转染和感染过程中合成的VP22的磷酸化谱相同。在这两种情况下，VP22仅在位于该蛋白N端120个残基内的丝氨酸残基上发生修饰。此外，体外磷酸化实验表明，组成型细胞激酶酪蛋白激酶II（Casein kinase II）在VP22的N端有四个丝氨酸共有识别位点，它以与体内观察到的相同方式使VP22磷酸化。该激酶还能在完整的衣壳-被膜结构中使VP22的N端磷酸化。因此，酪蛋白激酶II很可能是感染期间VP22的主要激酶。
