CHARACTERIZATION OF THE NONSTRUCTURAL PROTEINS OF ADENO ASSOCIATED VIRUS

腺相关病毒，AAV， 是由一个单一的开放阅读框架，rep基因编码，并不同于 通过利用下游启动子和切除下游启动子， 内含子。 两个较大的Rep蛋白作为复制起点 结合和起始蛋白，并且是病毒DNA合成所必需的。 以前，我们已经证明，两个较大的Rep蛋白，Rep 68和Rep 78是识别序列基序的DNA结合蛋白， 原型是AAV反向末端重复内的GAGC重复 （ITR）。 Rep蛋白的DNA结合能力可能解释了 Rep蛋白对基因表达的调节作用， 几个实验室观察到。 然而，这种影响似乎是 不依赖于典型Rep结合位点的存在， 转录基因的调控区。 其他细胞表型 与Rep 68或Rep 78表达相关的包括：活力丧失， 抑制细胞分裂和抑制病毒转化 致癌基因 这些效应可能是由Rep与一种 细胞蛋白 Rep蛋白的结构域是Rep寡聚化所必需的， 之前曾报告过。 然而，特定的残留物 这些交互作用所需的时间尚未定义。 为了 确定哪些残基参与蛋白质间相互作用，我们 已经进行了一系列的突变，改变了Rep 78的一个残基。 我们 分析色谱法的结果表明，Rep 78或Rep 68 形成具有与六聚体一致的性质的复合物， 其他DNA解旋酶复合物。 定义多肽如何与 其他蛋白质使我们能够概括和预测其他蛋白质 互动可能会发生。 Rep与表位的结合 噬菌体导致了克隆的选择， 重复的主题 我们正在确定细胞是否 含有这些表位的蛋白质与Rep 78相互作用，如果是这样， 是对细胞过程的影响。

The four non-structural proteins (Rep) of adeno-associated virus, AAV, are encoded by a single open reading frame, the rep gene, and differ from each other by utilization of an downstream promoter and excision of an intron. The two larger Rep proteins function as replication origin binding and initiation proteins and are required for viral DNA synthesis. Previously, we have demonstrated that the two larger Rep proteins, Rep 68 and Rep 78, are DNA binding proteins that recognize a sequence motif, the prototype is the GAGC repeat within the AAV inverted terminal repeat (ITR). The DNA binding ability of Rep proteins may have explained the regulatory effects of Rep proteins on gene expression that has been observed by several laboratories. However, this effect appears to be independent of the presence of a canonical Rep binding site within the regulatory region of the transcribed gene. Other cellular phenotypes associated with Rep 68 or Rep 78 expression include: loss of viability, inhibition of cell division, and inhibition of transformation by viral oncogenes. These effects may be induced by Rep association with a cellular protein. Domains of Rep proteins that are necessary for Rep oligomerization have been reported previously. However, the residues that are specifically required for these interactions have not been defined. In order to identify which residues are involved with inter-protein interactions, we have made a series of mutations altering a single residue Rep 78. Our results with analytical chromatography demonstrate that Rep 78 or Rep 68 forms a complex with properties consistent with a hexamer similar to other DNA helicase complexes. Defining how a polypeptide interacts with other proteins enables us to generalize and predict what other interactions may occur. Binding of Rep to epitopes displayed on bacteriophage has resulted in selection of clones with a commonly repeated motif. We are in the process of determining whether cellular proteins containing these epitopes interact with Rep 78 and if so, what are the effects on the cellular processes.