Evolution of Bacterial Copper Resistance

9306559 Cooksey这个项目是为了研究植物相关细菌如何适应环境中铜的有毒水平。铜是一种重要的杀菌剂，常用于农业植物的病害防治。植物病原细菌对铜的抗性发展可能会对未来铜在植物病害防治中的应用构成威胁，而更好地了解这种抗性是如何发展的对于评估这种威胁将是重要的。对铜抗性的认识已经导致了试图开发新的铜配方来规避抗性机制，而对抗性的生理和调节机制的更多了解可能会加强这一努力。微生物对汞等非必需有毒金属的耐受性已被广泛研究，但对铜的耐受性受到的关注要少得多。与其他金属不同。有爱的生物体需要铜作为某些酶的组成部分；在低水平下它是有益的，但在高水平下它是有毒的。因此，微生物种群中铜抗性的演变涉及铜吸收和排除机制的复杂平衡。克隆和鉴定了决定铜抗性的基因，发现它们与在铜敏感细菌中发现的一组染色体基因有关。我们已经证明了抗性可以通过这些染色体基因的修改来进化，本项目是进一步定义这些修改。由于微生物需要铜作为一种微量元素，因此阻止铜吸收的抗性机制必须受到严格的监管控制，这样铜才不会在正常生长条件下被排除在外。我们有证据表明，在这个系统中，基因表达水平的改变。细菌产生的其他蛋白的铜结合能力在铜排斥机制中是重要的，我们将研究这些蛋白的铜结合部位在抗性进化过程中是如何被修饰的。

9306559 Cooksey This project is to investigate how plant associated bacteria adapt to toxic levels of copper in the environment. Copper is an important bactericide used frequently for disease control on agricultural plants. The development of copper resistance in plant pathogenic bacteria may pose a threat to the future use of copper in plant disease control, and a better understanding of how this resistance develops will be important for evaluating this threat. The recognition of copper resistance has already led to attempts to develop new copper formulations that may circumvent resistance mechanisms, and a greater understanding of the physiological and regulatory mechanisms of resistance could enhance that effort. %%% Microbial resistance to nonessential toxic metals, such as mercury, has been studied extensively, but resistance to copper has receives much less attention. Unlike the other metals. copper is required by loving organisms as a component of certain enzymes; at low levels it is beneficial, but at high levels it is toxic. The evolution of copper resistance in microbial populations therefore involves a complex balance in copper uptake and exclusion mechanisms. The genes determining copper resistance were cloned and characterized, and they were found to be related to a set of chromosomal genes found in copper sensitive bacteria. We have shown that the resistance can evolve through modifications of these chromosomal genes, and the present project is to define further these modifications. Since copper is required by microorganisms as a trace element, the resistance mechanism, which prevents uptake of copper, must be under tight regulatory control so that copper is not excluded under normal growth conditions. We have evidence that modifications in the level in gene expression in this system. The copper binding capacity of other proteins produced by the bacterium is important in the copper exclusion mechanism, and we will study how copper binding sites of these proteins have been modified during the evolution of resistance.