Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 3Z5.
Michael G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8S 3Z5
Proc Natl Acad Sci U S A. 2014 May 13;111(19):7102-7. doi: 10.1073/pnas.1402358111. Epub 2014 Apr 28.
Many environmental bacteria are multidrug-resistant and represent a reservoir of ancient antibiotic resistance determinants, which have been linked to genes found in pathogens. Exploring the environmental antibiotic resistome, therefore, reveals the diversity and evolution of antibiotic resistance and also provides insight into the vulnerability of clinically used antibiotics. In this study, we describe the identification of a highly conserved regulatory motif, the rifampin (RIF) -associated element (RAE), which is found upstream of genes encoding RIF-inactivating enzymes from a diverse collection of actinomycetes. Using gene expression assays, we confirmed that the RAE is involved in RIF-responsive regulation. By using the RAE as a probe for new RIF-associated genes in several actinomycete genomes, we identified a heretofore unknown RIF resistance gene, RIF phosphotransferase (rph). The RPH enzyme is a RIF-inactivating phosphotransferase and represents a new protein family in antibiotic resistance. RPH orthologs are widespread and found in RIF-sensitive bacteria, including Bacillus cereus and the pathogen Listeria monocytogenes. Heterologous expression and in vitro enzyme assays with purified RPHs from diverse bacterial genera show that these enzymes are capable of conferring high-level resistance to a variety of clinically used rifamycin antibiotics. This work identifies a new antibiotic resistance protein family and reinforces the fact that the study of resistance in environmental organisms can serve to identify resistance elements with relevance to pathogens.
许多环境细菌具有多药耐药性，是古老抗生素耐药决定因素的储库，这些决定因素与病原体中的基因有关。因此，探索环境抗生素耐药组可揭示抗生素耐药性的多样性和进化，还可深入了解临床使用的抗生素的脆弱性。在本研究中，我们描述了一种高度保守的调控模体（rifampin [RIF] -associated element，RAE）的鉴定，该模体位于编码来自各种放线菌的 rifampin 失活酶的基因上游。通过基因表达测定，我们证实 RAE 参与了 RIF 响应性调控。通过将 RAE 用作几种放线菌基因组中几个新的 RIF 相关基因的探针，我们鉴定了一个迄今为止未知的 RIF 耐药基因 rifampin 磷酸转移酶（rph）。RPH 酶是一种 rifampin 失活磷酸转移酶，代表抗生素耐药性中的一个新蛋白家族。RPH 同源物广泛存在于 RIF 敏感细菌中，包括蜡状芽孢杆菌和病原体李斯特菌单核细胞增生症。来自不同细菌属的 RPH 的异源表达和体外酶测定表明，这些酶能够赋予各种临床使用的 rifamycin 抗生素高水平的耐药性。这项工作鉴定了一个新的抗生素耐药蛋白家族，并证实了这样一个事实，即对环境生物中的耐药性进行研究可以识别与病原体相关的耐药元件。
