SPONTANEOUS AND GENOTOXICANT INDUCED MUTATION MECHANISMS

描述：自发突变和由 环境致癌物质可导致人类遗传性疾病 癌症。在这份提案中，申请人将使用大肠杆菌继续 来检验某些DNA序列可以形成的假设 促进特异性突变的二级结构底物 事件发生的频率很高，或者在某些情况下会阻止特定的 突变。用于诱变的二级结构底物可以包括 十字形结构，由反向重复的DNA序列形成； 错配结构，在DNA复制过程中形成 直接重复序列；以及其他非沃森-克里克双链， 三联体或四联体结构。能够采用这种方式的DNA 另一种构象广泛存在于人类基因组中。Dr。 辛登的实验室已经开发出一种灵敏的体内检测方法 十字架和将继续确定之间的关系 十字架在体内的存在及其相对致突变性 潜力。反向重复序列似乎因未对齐而被删除 由形成十字形的发夹或在单链DNA中稳定的 在牢房里。他的实验室也发现了对氯霉素的抗药性。 逆转试验测量缺失和复制的频率 在17-23个碱基的“突变插入”DNA序列的直接重复之间 其可以形成限定的二级结构衬底。使用这个 系统，他们将继续识别分子中间体和 涉及直接重复之间的缺失和复制的机制。 辛登博士的实验室将继续验证这一假设 由导致删除的三向连接稳定的未对齐 优先出现在滞后的链中。通过合成和 对特殊设计的准回文的突变分析，他们 将继续调查导致这种疾病的分子机制 将准回文更正为完美的反向重复，这 似乎涉及发生在分子间的链交换 在DNA复制过程中优先位于前导链中。他们会 还研究了参与DNA复制的基因的作用， 重组和修复在自发的DNA定向突变中 确定负责引入的蛋白质和酶 基因组中的突变。环境致突变剂对人体健康的影响 DNA定向突变的频率不仅应该用于 确定为此类活动提供便利的代理，但还应 提供对分子机制的洞察。

DESCRIPTION: Spontaneous mutation and mutations induced by environmental carcinogens can lead to human genetic disease and cancer. In this proposal, the applicant will use E. coli to continue to test the hypothesis that certain sequences of DNA can form secondary structure substrates, which promote specific mutation events at a high frequency or, in some cases, prevent a specific mutation. Secondary structure substrates for mutagenesis can include cruciform structures, formed from inverted repeated DNA sequences; slipped mis-paired structures, formed during DNA replication in direct repeated sequences; and other non Watson-Crick duplex, triplex, or quadruplex structures. DNA that can adopt such alternative conformations occurs widely in the human genome. Dr. Sinden's laboratory has developed a sensitive in vivo assay for cruciforms and will continue to determine the relationship between the in vivo existence of cruciforms and their relative mutagenic potential. Inverted repeats appear to be deleted by misalignment stabilized by a hairpin formed as a cruciform or in single-stranded DNA in the cell. His lab has also developed a chloramphenicol resistance reversion assay to measure the frequency of deletion and duplication between direct repeats of 17-23 bp "mutation insert" DNA sequences that can form defined secondary structure substrates. Using this system, they will continue to identify the molecular intermediates and mechanisms involved in deletion and duplication between direct repeats. Dr. Sinden's laboratory will continue to test out the hypothesis that misalignment stabilized by a three-way junction leading to deletion occurs preferentially in the lagging strand. By the synthesis and mutational analysis of specifically designed quasipalindromes, they will continue to investigate the molecular mechanism responsible for the correction of quasipalindromes to perfect inverted repeats, which appears to involve an intermolecular strand switch that happens preferentially in the leading strand during DNA replication. They will also investigate the role of genes involved in DNA replication, recombination, and repair in spontaneous DNA directed mutagenesis to identify proteins and enzymes responsible for the introduction of mutations into the genome. The influence of environmental mutagens on the frequency of DNA directed mutation should not only serve to identify agents that facilitate this type of event, but should also provide insight into molecular mechanisms.