Geiss Brian J, Cano Gina L, Tavis John E, Morrison Lynda A
Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, MO 63104-1083, USA.
Virology. 2004 Dec 5;330(1):74-81. doi: 10.1016/j.virol.2004.08.034.
Phosphorylation of the herpes simplex virus (HSV) VP22 protein is regulated by cellular kinases and the UL13 viral kinase, but the sites at which these enzymes induce phosphorylation of HSV-2 VP22 are not known. Using serine-to-alanine mutants to map phosphorylation sites on HSV-2 VP22 in cells, we made three major observations. First, phosphorylation by a cellular kinase mapped to serines 70, 71, and/or 72 within CKII consensus sites analogous to previously identified phosphorylation sites in HSV-1 VP22. Second, we mapped UL13-mediated phosphorylation of HSV-2 VP22 to serines 28 and 34, describing for the first time UL13-dependent phosphorylation sites on VP22. Third, previously identified VP22-associated cellular kinase sites in HSV-1 VP22 (serines 292 and 294) were not phosphorylated in HSV-2 VP22 (serines 291 and 293). VP22 expressed alone accumulated in the cytoplasm and to a lesser extent in the nucleus. Phosphorylation by endogenous cellular kinase(s) did not alter the localization of VP22. Co-expression of HSV-2 VP22 with active UL13, but not with enzymatically inactive UL13, resulted in nuclear accumulation of VP22 and altered nuclear morphology. Surprisingly, redistribution of VP22 to the nucleus occurred independently of UL13-induced phosphorylation of VP22. The altered nuclear morphology of UL13-expressing cells was not due to apoptosis. These results demonstrate that phosphorylation of HSV-2 VP22 at multiple serine residues is induced by UL13 and cellular kinase(s), and that the nuclear/cytoplasmic distribution of VP22 is independent of its phosphorylation status but is controlled indirectly by UL13 kinase activity.
单纯疱疹病毒（HSV）VP22蛋白的磷酸化受细胞激酶和UL13病毒激酶调控，但这些酶诱导HSV-2 VP22磷酸化的位点尚不清楚。我们利用丝氨酸到丙氨酸的突变体来定位细胞中HSV-2 VP22的磷酸化位点，得出了三个主要发现。第一，细胞激酶介导的磷酸化定位于CKII共有位点内的丝氨酸70、71和/或72，类似于先前在HSV-1 VP22中鉴定出的磷酸化位点。第二，我们将HSV-2 VP22的UL13介导的磷酸化定位于丝氨酸28和34，首次描述了VP22上依赖UL13的磷酸化位点。第三，先前在HSV-1 VP22中鉴定出的与VP22相关的细胞激酶位点（丝氨酸292和294）在HSV-2 VP22（丝氨酸291和293）中未被磷酸化。单独表达的VP22在细胞质中积累，在细胞核中积累程度较低。内源性细胞激酶的磷酸化并未改变VP22的定位。HSV-2 VP22与活性UL13共表达，但不与无酶活性的UL13共表达，导致VP22在细胞核中积累并改变核形态。令人惊讶的是，VP22重新分布到细胞核与UL13诱导的VP22磷酸化无关。表达UL13的细胞的核形态改变并非由于凋亡。这些结果表明，UL13和细胞激酶诱导HSV-2 VP22在多个丝氨酸残基处发生磷酸化，并且VP22的核/质分布与其磷酸化状态无关，但受UL13激酶活性间接控制。
