FUNCTIONS OF LEUKEMIA VIRUS R REGIONS

我们已经获得了初步数据，在5‘32内存在一个元素 某些小鼠白血病基因组中R组分的核苷酸 有助于转录活性的病毒(MULV) 病毒。MULV的R区，位于 转录的起始点，与那些 长臂猿白血病病毒、猴肉瘤病毒和猫科动物 白血病病毒。我们的初步数据表明二级结构 R序列的大小对元素的活性很重要。另外， R区元件至少部分作用于增加RNA聚合酶II 装载到病毒LTR模板上，如在核连续分析中检测到的那样。 我们建议在这里进行一系列详细的研究来调查 MuLV元素的工作原理。特别是，我们假设 MuLV R区域元素的功能类似于 HIV-1焦油成分。具体地说，我们假设一个细胞因素 存在在功能上等同于HIV-1 TAT并识别 MuLV R元件在RNA水平刺激转录 启动和/或RNA聚合酶处理。我们建议使用 用突变方法精确识别细胞内的哪些核苷酸 MuLV-R元素是活动的关键。一系列实验将 以测试MuLV序列是作为DNA还是作为RNA发挥功能 半个月。我们还将确定它们是否会严格影响 转录启动或它们是否影响RNA的加工能力 加载到病毒转录模板上的聚合酶分子。其他 将对病毒进行检查，以确定它们是否含有类似的成分 以及序列上下文对MuLV功能的要求 元素是。我们还将测试MuLV序列是否至少可以 部分取代了HIV-1的TAR元素。蛋白质-核酸 结合分析将被用来寻找识别 MuLV R区域元素。

We have obtained preliminary data that an element exists within the 5' 32 nucleotides of the R components of the genomes of certain murine leukemia viruses (MuLVs) that contributes to the transcriptional activity of the virus. The R regions of the MuLVs, which are situated downstream of the initiation site of the transcription, bear striking similarity to those of the gibbon ape leukemia virus, simian sarcoma virus, and feline leukemia viruses. Our preliminary data indicate that secondary structure of the R sequences is important for the activity of the element. Also, the R region element acts at least in part to increase RNA polymerase II loading onto viral LTR templates, as detected in nuclear run-on assays. We propose here to perform a detailed series of studies to investigate how the MuLV element functions. In particular, we hypothesize that the MuLV R region element functions in a manner analogous to that of the HIV-1 TAR element. Specifically, we hypothesize that a cellular factor exists that is functionally equivalent to HIV-1 Tat and recognizes the MuLV R element at the level of RNA to stimulate transcriptional initiation and/or RNA polymerase processivity. We propose to use a mutagenesis approach to identify precisely which nucleotides within the MuLV R element are critical for activity. A series of experiments will be performed to test whether the MuLV sequences function as a DNA or RNA moiety. We will also determine whether they strictly affect transcriptional initiation or whether they affect processivity of RNA polymerase molecules loaded onto viral transcriptional templates. other viruses will be examined to see whether they contain a similar element and what the sequence context requirements for the function of the MuLV element are. We will also test whether the MuLV sequence can at least partially substitute for the HIV-1 TAR element. Protein-nucleic acid binding assays will be used to look for cellular factors that recognize the MuLV R region element.