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首页> 外文期刊>Molecular and Cellular Biology >Multiple proteins bind to VA RNA genes of adenovirus type 2.
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Multiple proteins bind to VA RNA genes of adenovirus type 2.

机译：多种蛋白质与2型腺病毒的VA RNA基因结合。

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Using fractionated HeLa cell nuclear extracts and both nuclease (DNase I) cleavage and chemical cleavage (methidiumpropyl-EDTA X Fe(II) protection methodologies, we demonstrated the presence of three proteins which interacted specifically, yet differentially, with the two VA genes of adenovirus type 2. One, previously identified as transcription initiation factor TFIIIC, bound to a site centered on the transcriptionally essential B-block concensus element of the VAI gene and, with a lower affinity, to the analogous site in the VAII gene. Another, identified as the cellular protein involved in adenovirus replication, nuclear factor I, bound to sites immediately downstream from the two VAI terminators (at approximately +160 and +200). The third, a previously unrecognized VA gene binding protein termed VBP, bound immediately upstream of the B-block element in the VAI gene but showed no binding to VAII. Possible roles for these proteins in VA gene transcription were investigated in in vitro assay systems reconstituted with partially purified transcription factors (RNA polymerase III, TFIIIB, and TFIIIC). Although TFIIIC activity was present predominantly in fractions containing B-block binding activity, there was not complete correspondence between functional and DNA binding activities. The nuclear factor I-like protein had no effect when added to a complete transcription reaction. The presence of VBP appeared to depress the intrinsic ratio of VAI-VAII synthesis, thereby simulating the relative transcription levels observed early in adenovirus infection of HeLa cells. These observations suggest a model, involving both intragenic binding factors (VBP and TFIIIC) and variable template concentrations, for the differential regulation of VA transcription during the course of adenovirus infection.
机译：使用分级的HeLa细胞核提取物以及核酸酶（DNase I）裂解和化学裂解（甲基丙基-EDTA X Fe（II）保护方法），我们证明了三种蛋白质的存在，这些蛋白质与腺病毒的两个VA基因特异性地但有差异地相互作用类型2。一种，以前被鉴定为转录起始因子TFIIIC，与以VAI基因的转录必需B嵌段共有元件为中心的位点结合，并以较低的亲和力与VAII基因的类似位点结合。作为参与腺病毒复制的细胞蛋白，核因子I结合在两个VAI终止子的下游位点（大约+160和+200）;第三个是以前未被识别的VA基因结合蛋白，称为VBP，它直接结合在VAI上游。 VAI基因中的B-block元素但不与VAII结合。体外研究了这些蛋白在VA基因转录中的可能作用o用部分纯化的转录因子（RNA聚合酶III，TFIIIB和TFIIIC）重建的测定系统。尽管TFIIIC活性主要存在于含有B-block结合活性的部分中，但功能和DNA结合活性之间并不完全对应。当添加到完整的转录反应中时，核因子I样蛋白没有作用。 VBP的存在似乎降低了VAI-VAII合成的内在比率，从而模拟了在HeLa细胞的腺病毒感染中早期观察到的相对转录水平。这些观察结果提出了一种模型，该模型涉及基因内结合因子（VBP和TFIIIC）和可变模板浓度，用于腺病毒感染过程中VA转录的差异调节。

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