Gunasinghe S K, Hubbs A E, Wright C F
Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
J Biol Chem. 1998 Oct 16;273(42):27524-30. doi: 10.1074/jbc.273.42.27524.
A factor designated VLTF-X is required to support vaccinia virus late transcription in vitro. It has been found that a late promoter DNA binding activity cochromatographs and cosediments with VLTF-X activity. Current experiments show that VLTF-X activity is present in a variety of uninfected mammalian cell types and is indistinguishable from that recovered from infected cells based upon several criteria. VLTF-X activity from both sources displays the same purification profile over phosphocellulose and DNA affinity resins and has the same sedimentation coefficient. In addition, the factors purified from both infected and uninfected cells form protein-DNA complexes of identical electrophoretic mobility in the presence of vaccinia virus late promoter-containing DNA. The affinity of these factors for the late promoter probes is identical and late promoter-specific based on competition experiments. Moreover, VLTF-X purified from both sources bound to late promoter-containing DNA in the presence or absence of MgCl2 and ATP and formed complexes resistant to heat inactivation. These experiments offer proof that vaccinia virus factor VLTF-X is a host cell protein that supports transcription of the viral late genes.
一种名为VLTF-X的因子是体外支持痘苗病毒晚期转录所必需的。已发现一种晚期启动子DNA结合活性与VLTF-X活性共层析并共沉降。目前的实验表明，VLTF-X活性存在于多种未感染的哺乳动物细胞类型中，并且根据几个标准，它与从感染细胞中回收的活性没有区别。来自这两种来源的VLTF-X活性在磷酸纤维素和DNA亲和树脂上显示出相同的纯化图谱，并且具有相同的沉降系数。此外，从感染和未感染细胞中纯化的因子在含有痘苗病毒晚期启动子的DNA存在下形成具有相同电泳迁移率的蛋白质-DNA复合物。基于竞争实验，这些因子对晚期启动子探针的亲和力相同且具有晚期启动子特异性。此外，从这两种来源纯化的VLTF-X在存在或不存在MgCl2和ATP的情况下都能与含有晚期启动子的DNA结合，并形成耐热失活的复合物。这些实验证明痘苗病毒因子VLTF-X是一种支持病毒晚期基因转录的宿主细胞蛋白。
