Characterizing novel Beta-lactamases from metagenomic samples: insights into the evolution of antimicrobial resistance from the environment towards human-associated pathogens

项目摘要 β-内酰胺酶是β-内酰胺类抗生素最常见的耐药机制。特别 值得关注的是一组称为碳青霉烯酶的β-内酰胺酶，因其破坏 我们最新的β-内酰胺类抗生素碳青霉烯类碳青霉烯耐药性的上升是最近 全球性的趋势导致了全国性的恐惧。一个有趣的方法来理解 碳青霉烯耐药性及其演变是通过定量分析非致病性 环境中发现的微生物。对这些微生物的分析提供了有趣的 预测抗生素耐药性如何演变的可能性，并为临床医生提供 病原菌新耐药机制出现的“预警”系统。 先前的研究表明，土壤是许多β-内酰胺酶的良好储存库， 尤其是碳青霉烯酶。该项目的主要部分将是研究一系列 从阿拉斯加土壤中分离到一种宏基因组来源的β-内酰胺酶，命名为LRA（“β-内酰胺耐药 阿拉斯加”）。这种宏基因组学方法将被扩展并应用于土壤的分析 来自南极洲的样本，以确定不同隔离地区的β-内酰胺酶介导的耐药性。 将使用多管齐下的方法对已鉴定的环境β-内酰胺酶进行表征 涉及表型、分子、生物化学和结构技术。具体而言，结果来自 这一全面的分析将使我们能够评估所发现的β-内酰胺酶的进化途径， 在当今困扰人类健康的临床病原体中， 可能被这些病原体招募的潜在未开发基因。

PROJECT SUMMARY β-Lactamases are the most widespread resistance mechanism to β-lactam antibiotics. Of particular concern are a group of β-lactamases known as carbapenemases, named for their ability to destroy our newest β-lactam antibiotics, the carbapenems. The rise of carbapenem resistance is a recent global trend that has resulted in pan-national fear. An interesting approach to understand carbapenem resistance and how it evolves is through quantitative analysis of non-pathogenic microorganisms found in the environment. Analysis of these microorganisms offers the intriguing possibility of predicting how antibiotic resistance may evolve and provides clinicians with an “early warning” system for the advent of novel resistance mechanisms in pathogenic bacteria. Previous research has shown that the soil is an excellent repository for many β-lactamases, especially carbapenemases. The main part of the project will be the study of a collection of metagenome-origin β-lactamases isolated from Alaskan soil, named LRA (for “β-lactam resistance from Alaska”). This metagenomic approach will be expanded and applied to the analysis of soil samples from Antarctica to identify β-lactamase-mediated resistance in different isolated regions. Identified environmental β-lactamases will be characterized using a multi-pronged approach involving phenotypic, molecular, biochemical and structural techniques. Specifically, results from this comprehensive analysis will allow us to assess the evolutionary routes of β-lactamases found among clinical pathogens that plague human health today, and to evaluate novel niches of potentially unexplored genes that could be recruited by these pathogens.