ERROR PRONE DNA SYNTHESIS AND ONCOGENE MUTAGENESIS

在DNA中添加或删除核苷酸的突变 序列在病理学中起主要作用。 微卫星不稳定性 信号细胞的易感性移码突变的关键 在肿瘤发生中的重要性。 三重重复序列的扩增引发了 一系列神经肌肉疾病的发病机制。 内在的稳定性 DNA的序列决定了DNA的序列， 是由一组蛋白质的监视活动来确保的。 我们 建议：a）确定结构因素的相对重要性 通过系统地测量突变， 不同长度和碱基组成的重复核苷酸序列。 为 为此，我们计划构建一种基质， 可以将序列置于特定位置以设置报告基因 在帧内或帧外; B）我们提出测试假设， 复制型大肠杆菌DNA的dnaE和dnaN亚基 聚合酶通过将（重复的）DNA核苷酸锚定到 蛋白质中的特定氨基酸; c）真核错配修复 蛋白质（mutS同源物）专门用于碱基的校正， 替换或滑动错误。 我们将确定细菌是否 mutS蛋白可以区分这两种类型的错误， 选择错配修复突变体，其主要校正一个或多个错配修复突变体， （d）校对活动需要校对人员的联系 外切核酸酶与聚合酶亚基。 我们将决定 校对由外切核酸酶的修饰或由外切核酸酶的修饰引起。 改变与其他亚基结构域的相互作用。 我们的目标是学习 通过突变分析， 识别并与DNA中的重复位点相互作用， 控制滑移 我们认为，这种理解将导致 干预策略，以控制个人缺乏的下滑， 监督过程的各个阶段。

Mutations in which nucleotides are added or deleted from the DNA sequence play a major role in pathology. Microsatellite instability signals the susceptibility of cells to frameshift mutations of critical importance in tumorigenesis. Expansion of triplet repeats sets off the pathogenesis of a set of neuromuscular diseases. The innate stability of the DNA is determined by its sequence but the maintenance of sequence is ensured by the surveillance activities of a set of proteins. We propose: a) to determine the relative importance of structural factors in DNA that lead to slippage by systematically measuring mutations in repeat nucleotide runs of different length and base composition. For this purpose we plan to construct a substrate in which any target sequence can be placed in a particular position to set a reporter gene either in- or out-of-frame; b) We propose to test the hypothesis that the dnaE and dnaN subunits of the replicative Escherichia coli DNA polymerase reduce slippage by anchoring (repeated) DNA nucleotides to particular amino acids in protein; c) Eukaryotic mismatch repair proteins (mutS homologs) are specialized for the correction of base substitution or slippage errors. We will determine if the bacterial mutS protein can distinguish between the two types of errors by selecting for mismatch repair mutants correcting primarily one or the other; d) Proofreading activity requires association of the proofreading exonuclease with the polymerase subunit. We will determine whether proofreading results from modification of the exonuclease or from an altered interaction with other subunit domains. Our goal is to learn by mutational analysis the location of the amino acid sites in proteins which recognize and interact with repeated sites in DNA to prevent or control slippage. We suppose that this understanding will lead to intervention strategies to control slippage in individuals deficient in particular stages of the surveillance process.