Infection and Immunity Programme, Monash Biomedicine Discovery Institute, Monash University, Victoria, Australia; Department of Microbiology, Monash University, Victoria, Australia.
Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Victoria, Australia.
Int J Antimicrob Agents. 2018 Apr;51(4):586-593. doi: 10.1016/j.ijantimicag.2017.12.016. Epub 2017 Dec 27.
The rapid emergence of Gram-negative 'superbugs' has become a significant threat to human health globally, and polymyxins have become a last-line therapy for these very problematic pathogens. Polymyxins exhibit their antibacterial killing by initial interaction with lipid A in Gram-negative bacteria. Polymyxin resistance can be mediated by phosphoethanolamine (PEA) modification of lipid A, which abolishes the initial electrostatic interaction with polymyxins. Both chromosome-encoded (e.g. EptA, EptB and EptC) and plasmid-encoded (e.g. MCR-1 and MCR-2) PEA transferases have been reported in Gram-negative bacteria; however, their sequence and functional heterogeneity remain unclear. This article reports a comparative analysis of PEA transferases across 10 clinically relevant Gram-negative bacterial species using multiple sequence alignment and phylogenetic analysis. The results show that the pairwise identities among chromosome-mediated EptA, EptB and EptC from Escherichia coli are low, and EptA shows the greatest similarity with MCR-1 and MCR-2. Among PEA transferases from representative strains of 10 clinically relevant species, the catalytic domain is more conserved compared with the transmembrane domain. In particular, PEA acceptor sites and zinc-binding pockets show high conservation between different species, indicating their potential importance for the function of PEA transferases. The evolutionary relationship of MCR-1, MCR-2 and EptA from the 10 selected bacterial species was evaluated by phylogenetic analysis. Cluster analysis illustrates that 325 EptA from 275 strains of 10 species within each individual species are highly conserved, whereas interspecies conservation is low. This comparative analysis provides key bioinformatic information to better understand the mechanism of polymyxin resistance via PEA modification of lipid A.
革兰氏阴性“超级细菌”的迅速出现已成为全球人类健康的重大威胁，而多黏菌素已成为治疗这些非常棘手病原体的最后一线药物。多黏菌素通过与革兰氏阴性菌的脂质 A 初始相互作用发挥其杀菌作用。多黏菌素耐药性可由脂质 A 的磷酸乙醇胺（PEA）修饰介导，从而消除与多黏菌素的初始静电相互作用。已在革兰氏阴性菌中报道了染色体编码（如 EptA、EptB 和 EptC）和质粒编码（如 MCR-1 和 MCR-2）的 PEA 转移酶；然而，它们的序列和功能异质性仍不清楚。本文使用多序列比对和系统发育分析报告了 10 种临床相关革兰氏阴性细菌中 PEA 转移酶的比较分析。结果表明，大肠杆菌中染色体介导的 EptA、EptB 和 EptC 之间的成对同一性较低，EptA 与 MCR-1 和 MCR-2 最相似。在 10 种临床相关代表菌株的 PEA 转移酶中，与跨膜结构域相比，催化结构域的保守性更高。特别是，PEA 接受位点和锌结合口袋在不同物种之间显示出高度保守，表明它们对 PEA 转移酶的功能具有潜在重要性。通过系统发育分析评估了 10 种选定细菌中 MCR-1、MCR-2 和 EptA 的进化关系。聚类分析表明，10 种细菌中每个种内的 325 个 EptA 来自 275 株高度保守，而种间保守性较低。这种比较分析提供了关键的生物信息学信息，以更好地了解通过脂质 A 的 PEA 修饰导致的多黏菌素耐药性的机制。
