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首页> 外文期刊>Molecular and Cellular Biology >Sequences involved in initiation of simian virus 40 late transcription in the absence of T antigen.
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Sequences involved in initiation of simian virus 40 late transcription in the absence of T antigen.

机译：在没有T抗原的情况下，参与猿猴病毒40后期转录起始的序列。

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We analyzed the sequences involved in vivo in the initiation of simian virus 40 (SV40) late transcription occurring in the absence of both SV40 origin sequences and T antigen. The constituent elements of the SV40 late promoters have already been the subject of extensive studies. In vitro studies have resulted in the description of two putative domains of the late promoters. The first domain consists of an 11-base-pair (bp) sequence, 5'-GGTACCTAACC-3', located 25 nucleotides (nt) upstream of the SV40 major late initiation site (MLIS) (J. Brady, M. Radonovich, M. Vodkin, V. Natarajan, M. Thoren, G. Das, J. Janik, and N. P. Salzman, Cell 31:624-633, 1982). The second domain is located within the G-C-rich region (J. Brady, M. Radonovich, M. Thoren, G. Das, and N. P. Salzman, Mol. Cell. Biol. 4:133-141; U. Hansen and P. A. Sharp, EMBO J. 2:2293-2303). Our previous in vivo studies permitted us to define a domain of the late promoter which extends from nt 332 to nt 113 and includes the 72-bp enhancer sequences. Here, by using transfection of the appropriate chimeric plasmids into HeLa cells in conjunction with quantitative S1 nuclease analysis, we analyzed in more detail the sequences required for the control of SV40 late-gene expression occurring before the onset of viral DNA replication. We showed that the major late promoter element is in fact the 72-bp repeat enhancer element. This element was able to drive efficient late transcription in the absence of T antigen. Under our experimental conditions, removal of the G-C-rich region (21-bp repeats) entailed a significant increase in the level of late-gene expression. Moreover, translocation of this element closer to the MLIS (53 nt upstream of the MLIS) enhanced the level of transcripts initiated at natural late initiation sites. Our results suggest that the G-C-rich regions have to be positioned between the enhancer element and the initiation sites to stimulate transcription from downstream sites. Thus, the relative arrangement of the various promoter elements is a critical factor contributing to the situation in which the early promoter is stronger than late promoters before viral DNA replication.
机译：我们分析了在猿猴病毒40（SV40）晚期转录的起始中涉及到的体内序列，这些序列在没有SV40起源序列和T抗原的情况下发生。 SV40晚期启动子的组成元件已经成为广泛研究的主题。体外研究导致了晚期启动子的两个推定结构域的描述。第一个域由11个碱基对（bp）序列5'-GGTACCTAACC-3'组成，位于SV40主要晚期起始位点（MLIS）上游25个核苷酸（nt）处（J. Brady，M. Radonovich， M.Vodkin，V.Nataarajan，M.Thoren，G.Das，J.Janik和NP Salzman，Cell 31：624-633，1982）。第二个域位于富含GC的区域内（J. Brady，M。Radonovich，M。Thoren，G。Das和NP Salzman，Mol。Cell。Biol。4：133-141; U。Hansen和PA Sharp ，EMBO J. 2：2293-2303）。我们先前的体内研究允许我们定义晚期启动子的结构域，其从nt 332延伸至nt 113，并包含72 bp的增强子序列。在这里，通过将适当的嵌合质粒转染到HeLa细胞中并进行定量S1核酸酶分析，我们更加详细地分析了控制SV40晚期基因表达所需的序列，该序列发生在病毒DNA复制开始之前。我们表明，主要的晚期启动子元件实际上是72 bp重复增强子元件。在没有T抗原的情况下，该元件能够驱动有效的后期转录。在我们的实验条件下，去除富含G-C的区域（21 bp重复）会大大增加后期基因表达的水平。此外，该元件易位更靠近MLIS（在MLIS上游53 nt）提高了在自然晚期起始位点起始的转录本水平。我们的结果表明，富含G-C的区域必须位于增强子元件和起始位点之间，以刺激下游位点的转录。因此，各种启动子元件的相对排列是导致病毒DNA复制之前早期启动子强于晚期启动子的情况的关键因素。

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