Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, SE-58185 Linköping, Sweden.
Department of Biomedical and Clinical Sciences, Linköping University and Department of Clinical Microbiology, University Hospital, SE-58185 Linköping, Sweden.
Int J Mol Sci. 2021 Jan 8;22(2):576. doi: 10.3390/ijms22020576.
The nosocomial opportunistic Gram-negative bacterial pathogen is resistant to multiple antimicrobial agents and an emerging global health problem. The polymyxin antibiotic colistin, targeting the negatively charged lipid A component of the lipopolysaccharide on the bacterial cell surface, is often considered as the last-resort treatment, but resistance to colistin is unfortunately increasing worldwide. Notably, colistin-susceptible can also develop a colistin dependence after exposure to this drug in vitro. Colistin dependence might represent a stepping stone to resistance also in vivo. However, the mechanisms are far from clear. To address this issue, we combined proteogenomics, high-resolution microscopy, and lipid profiling to characterize and compare colistin-susceptible clinical isolate (Ab-S) of to its colistin-dependent subpopulation (Ab-D) obtained after subsequent passages in moderate colistin concentrations. Incidentally, in the colistin-dependent subpopulation the gene was disrupted by insertion of IS, the lipid A biosynthesis terminated, and Ab-D cells displayed a lipooligosaccharide (LOS)-deficient phenotype. Moreover, both and genes were perturbed by insertions of IS and IS, and LOS-deficient bacteria displayed a capsule with decreased thickness as well as other surface imperfections. The major changes in relative protein abundance levels were detected in type 6 secretion system (T6SS) components, the resistance-nodulation-division (RND)-type efflux pumps, and in proteins involved in maintenance of outer membrane asymmetry. These findings suggest that colistin dependence in involves an ensemble of mechanisms seen in resistance development and accompanied by complex cellular events related to insertional sequences (ISs)-triggered LOS-deficiency. To our knowledge, this is the first study demonstrating the involvement of IS and IS IS elements in the modulation of the lipid A biosynthesis and associated development of dependence on colistin.
医院获得性机会性革兰氏阴性细菌病原体对多种抗菌药物具有耐药性，是一个新出现的全球健康问题。多粘菌素类抗生素黏菌素针对细菌细胞表面脂多糖的带负电荷的脂质 A 成分，通常被认为是最后的治疗手段，但不幸的是，世界各地对黏菌素的耐药性正在增加。值得注意的是， 即使在体外接触这种药物后，也可能对黏菌素产生依赖性。黏菌素依赖性也可能代表体内耐药性的一个垫脚石。然而，其机制还远不清楚。为了解决这个问题，我们结合蛋白质组学、高分辨率显微镜和脂质分析，对黏菌素敏感的临床分离株（Ab-S）及其在中等浓度黏菌素后续传代后获得的黏菌素依赖性亚群（Ab-D）进行了特征描述和比较。顺便说一句，在黏菌素依赖性亚群中， 基因被插入 IS 中断，脂质 A 生物合成终止，Ab-D 细胞表现出脂寡糖（LOS）缺陷表型。此外， 和 基因都被插入 IS 和 IS 扰乱，LOS 缺陷细菌显示出厚度减小的荚膜以及其他表面缺陷。相对蛋白丰度水平的主要变化检测到在类型 6 分泌系统（T6SS）组件、耐药-结节-分裂（RND）型外排泵以及与维持外膜不对称性相关的蛋白中。这些发现表明， 在 中的黏菌素依赖性涉及到耐药性发展中看到的一系列机制，并伴随着与插入序列（IS）触发的 LOS 缺陷相关的复杂细胞事件。据我们所知，这是第一项证明 IS 和 IS 以及 IS 元素参与脂质 A 生物合成的调节及其与对黏菌素的依赖性发展的研究。
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