Mechanism of adaptive amplification

自适应放大机制

• 批准号: 6400183
• 负责人: PHILIP John HASTINGS
• 金额: $ 22.58万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6400183
• 关键词: Escherichia coli; biochemical evolution; environmental stressor; gene mutation; gene targeting; genetic recombination; natural gene amplification; nucleic acid amplification techniques; nucleic acid sequence; polymerase chain reaction; regulatory gene; restriction mapping; southern blotting

Genetic change occurs not only by selection of preexisting variation. It also occurs adaptively. This means that the change occurs after cells are exposed to a selective environment, and is advantageous under the conditions of selection. The process of adaptive mutation in bacteria has been well studied and shown, in one system, to be a separate mechanism from spontaneous growth-dependent mutation. A second adaptive process, adaptive amplification, was recently discovered in this laboratory in the same bacterial system. In adaptive amplification, the cell makes numerous copies of a length of DNA carrying a gene that confers an advantage when expressed at a higher level. This project explores the molecular mechanism of amplification (including adaptive amplification) in Escherichia coli, using DNA sequencing, genetic manipulation and experimental intervention. The structure of amplified DNA will be defined, and the genetic requirements for adaptive amplification determined. Whether adaptive amplification is associated with other genetic instability, such as hyper-recombination and general chromosomal instability, will be tested. These results will help to define a mechanism by which DNA is amplified in response to environmental stress. The mechanism of amplification in E. coli is poorly understood at present. The results of this work will provide new insights into DNA transactions in cells under stress, and also to the general processes of chromosomal instability, and adaptation of cells to stressed environments. The results of this study will be relevant to many situations in which genetic change occurs under stress. These include the evolution of pathogenicity, the development of drug resistance in pathogens and in tumor cells, and the development of tumors. The recent discoveries of multiple different DNA repair process that are highly conserved between bacteria and humans, and the paucity of mechanistic information in the less tractable human system, underscore the relevance of this work to many aspects of human health.

基因变化不仅仅是通过选择先前存在的变异来发生的。它也是适应性地发生的。这意味着这种变化发生在细胞暴露在选择性环境中之后，并且在选择条件下是有利的。细菌中的适应性突变过程已经得到了很好的研究，并表明在一个系统中，这是一个独立于自发生长依赖突变的机制。该实验室最近在同一细菌系统中发现了第二个适应性过程，适应性扩增。在适应性扩增中，细胞复制大量携带基因的DNA拷贝，当基因在较高水平表达时，该基因具有优势。本项目通过DNA测序、遗传操作和实验干预，探索了在大肠杆菌中扩增(包括适应性扩增)的分子机制。将确定扩增DNA的结构，并确定适应性扩增的遗传要求。适应性扩增是否与其他遗传不稳定有关，如超重组和一般染色体不稳定，将被测试。这些结果将有助于确定DNA在应对环境压力时被放大的机制。目前，在大肠杆菌中扩增的机制尚不清楚。这项工作的结果将为研究应激下细胞中的DNA交易，以及染色体不稳定和细胞对应激环境的适应的一般过程提供新的见解。这项研究的结果将与许多在压力下发生基因变化的情况相关。这些包括致病性的进化，病原体和肿瘤细胞中耐药性的发展，以及肿瘤的发展。最近发现的多种不同的DNA修复过程在细菌和人类之间高度保守，而在不太容易处理的人类系统中缺乏机械信息，突显了这项工作与人类健康的许多方面的相关性。