Evolution of Copper Resistance in Plant Microbes

这项研究的目的是调查植物如何与 细菌适应环境中有毒的铜。 铜是一种重要的微量元素，常用于治疗疾病 控制农业植物和与之相关的微生物 因此，这些植物定期暴露于高水平的 这种金属。 植物抗铜性的研究进展 致病菌可能对铜的未来使用构成威胁 在植物病害控制方面， 抗药性的发展对评估这种威胁很重要。 此外，了解植物微生物如何产生铜 抗性可能有助于设计解毒方法 铜污染废水或转基因 植物和有益微生物对铜的耐受性增加 在农业环境中。 微生物对汞等有毒金属的抵抗力 已经被广泛研究，但铜电阻已经收到了很多 更少的关注。 与许多其他重餐不同，铜是 生物体所需的某些酶的组成部分; 低浓度时有益，高浓度时有毒。 微生物群体中铜抗性的进化必须 因此，涉及机制之间的平衡，以防止铜 毒性和维持细胞足够铜的能力 增长 Cooksey博士从一种细菌中分离出了耐铜细菌， 常规施用铜化合物的农业系统 用于控制细菌性疾病。 铜基因 已经克隆并鉴定了抗性。 这项建议 关于克隆基因的生化功能， 基因调控及其与同源基因的关系 最近在几种细菌中检测到。 库克西博士假设耐铜基因 是从产生正常含铜细胞的基因进化而来的 proteins. 这些蛋白质可能经过修饰， 铜和防止有毒金属达到高 细菌细胞内溶液的浓度。 以来 铜对生长至关重要，然而， 只有当铜的毒性水平存在时才应表示; 库克西博士已经证明耐药基因是铜- 诱导，这一建议涉及的基本机制， 铜诱导基因表达。

The proposed research 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, and microbes associated with those plants are therefore exposed periodically to high levels of this metal. 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. In addition, knowledge of how plant microbes develop copper resistance may be useful in designing methods for detoxifying copper in contaminated wastewaters or for genetically modifying plants and beneficial microbes for increased tolerance to copper in the agricultural environment. Microbial resistance to toxic metals such as mercury has been studied extensively, but copper resistance has received much less attention. Unlike many other heavy meals, copper is required by living 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 must therefore involve a balance between mechanisms to prevent copper toxicity and the ability to maintain enough copper for cell growth. Dr. Cooksey isolated copper-resistant bacteria from an agricultural system where copper compounds are routinely applied to plants for bacterial disease control. Genes encoding copper resistance have been cloned and characterized. This proposal concerns the biochemical function of the cloned genes, their genetic regulation, and their relationship to homologous genes that have recently been detected in several bacterial species. Dr. Cooksey has hypothesized that the copper resistance genes have evolved from genes that produce normal copper-containing proteins. These proteins may have been modified to bind more copper and prevent the toxic metal from reaching high concentrations in solution inside the bacterial cell. Since copper is essential for growth, however, the resistance genes should be expressed only when toxic levels of copper are present; Dr. Cooksey has shown that the resistance genes are copper- inducible, and this proposal addresses basic mechanisms of copper-inducible gene expression.