MECHANISMS OF MISTRANSLATION MEDIATED MUTATOR RESPONSE

描述：本提案描述了旨在表征 翻译和DNA复制之间的假定联系。 研究者已 获得了初步证据，表明存在可诱导的致突变反应 翻译应力诱导突变（translational stress induced mutagenesis，TSM） 他发现 穆塔和mutC增变基因在以下基因的反密码子中具有碱基替换： glyV或glyW tRNA基因允许突变tRNA解码天冬氨酸 密码子为甘氨酸。 突变子表型是组成型的， 研究人员认为，表型不是由于罕见的甘氨酸 DNA聚合酶III的DNA校正亚基中的取代。 在 此外，表型是recA依赖性的，但不需要功能性 umuD/C基因。 工作假设是，该途径是recA依赖性的 但不依赖于SOS，是对翻译压力的反应，而不是对翻译压力的反应。 这是误译本身的结果。 可能与β-淀粉样蛋白有关， 穆塔细胞中的关键事件在β亚基的上游。 博士 Humayun建议进行三组实验， 描述TSM响应。 第一组实验将测试 假设翻译应激而不是特定氨基酸 特定蛋白质中的取代诱导TSM，并将定义 诱导TSM的平移应力条件的范围。 第二组 实验将确定翻译压力是否会改变DNA 复制保真度通过比较DNA复制活动诱导和 在体外系统中的未诱导细胞。 第三个项目将描述 TSM反应与umuD/C依赖性SOS通路的不同。

DESCRIPTION: This proposal describes approaches designed to characterize a putative link between translation and DNA replication. The investigator has obtained preliminary evidence that there is an inducible mutagenic response called translational stress-induced mutagenesis (TSM). He found that the mutA and mutC mutator genes have a base substitution in the anticodons of the glyV or glyW tRNA genes that allow the mutant tRNAs to decode aspartate codons as glycine. The mutator phenotype is constitutive and the investigator argues that the phenotype is not due to rare glycine substitutions in the epsilon proofreading subunit of DNA polymerase III. In addition, the phenotype is recA-dependent but does not require functional umuD/C genes. The working hypothesis is that the pathway is recA-dependent but SOS-independent and is a response to translational stress rather than a result of mistranslation itself. The epsilon protein could be involved but the critical events in mutA cells are upstream of the epsilon subunit. Dr. Humayun proposes to carry-out three sets of experiments to further characterize the TSM response. The first set of experiments will test the hypothesis that translational stress rather than a specific amino acid substitution in a particular protein(s) induces TSM and will define the range of translational stress conditions that induce TSM. The second set of experiments will determine if translational stress will alter DNA replication fidelity by comparing DNA replication activities in induced and uninduced cells in an in vitro system. The third project will characterize how the TSM response differs from the umuD/C-dependent SOS pathway.