Department of Genome Sciences, University of Washington, Seattle, Washington, USA.
Department of Microbiology, University of Washington, Seattle, Washington, USA.
Antimicrob Agents Chemother. 2018 Mar 27;62(4). doi: 10.1128/AAC.00068-18. Print 2018 Apr.
Slow-growing bacteria are insensitive to killing by antibiotics, a trait known as antibiotic tolerance. In this study, we characterized the genetic basis of an unusually robust β-lactam (meropenem) tolerance seen in species. We identified tolerance genes under three different slow-growth conditions by extensive transposon mutant sequencing (Tn-seq), followed by single mutant validation. There were three principal findings. First, mutations in a small number of genes reduced tolerance under multiple conditions. Most of the functions appeared to be specific to peptidoglycan synthesis and the response to its disruption by meropenem action rather than being associated with more general physiological processes. The top tolerance genes are involved in immunity toward a type VI toxin targeting peptidoglycan (BTH_I0069), peptidoglycan recycling (), periplasmic regulation by proteolysis (), and an envelope stress response ( and ). Second, most of the tolerance functions did not contribute to growth in the presence of meropenem (intrinsic resistance), indicating that the two traits are largely distinct. Third, orthologues of many of the top tolerance genes were also important in Overall, these studies show that the determinants of meropenem tolerance differ considerably depending on cultivation conditions, but that there are a few shared functions with strong mutant phenotypes that are important in multiple species.
生长缓慢的细菌对抗生素的杀灭作用不敏感，这种特性被称为抗生素耐受性。在这项研究中，我们对 种中出现的一种异常强大的β-内酰胺（美罗培南）耐受性的遗传基础进行了特征描述。我们通过广泛的转座子突变体测序（Tn-seq），然后进行单个突变体验证，在三种不同的缓慢生长条件下鉴定了耐受性基因。有三个主要发现。首先，少数基因突变在多种条件下降低了耐受性。大多数功能似乎专门针对肽聚糖合成以及对美罗培南作用破坏的反应，而不是与更普遍的生理过程有关。顶级的耐受性基因涉及针对肽聚糖的 VI 型毒素的免疫（BTH_I0069）、肽聚糖回收（）、由蛋白水解作用调节的周质（）和包膜应激反应（和）。其次，大多数耐受性功能在美罗培南存在时并不促进生长（固有耐药性），表明这两个特性在很大程度上是不同的。第三，许多顶级耐受性基因的同源物在 中也很重要。总体而言，这些研究表明，美罗培南耐受性的决定因素取决于培养条件，差异相当大，但有一些与强突变表型共享的功能在多种 种中很重要。
