Gene Engineering Laboratory, Feed Research Institute, Chinese Academy of Agricultural Sciences, 12 Zhongguancun Nandajie St., Haidian District, Beijing, 100081, People's Republic of China.
Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing, 100081, People's Republic of China.
Appl Microbiol Biotechnol. 2022 Jan;106(1):211-226. doi: 10.1007/s00253-021-11708-x. Epub 2021 Dec 10.
The rising prevalence of antibiotic resistance poses the greatest health threats. Antimicrobial peptides (AMPs) are regarded as the potentially effective therapy. To avoid current crisis of antibiotic resistance, a comprehensive understanding of AMP resistance is necessary before clinical application. In this study, the development of resistance to the anti-Gram-negative bacteria peptide N6NH (21 residues, β-sheet) was characterized in E. coli ATCC25922. Three N6NH-resistant E. coli mutants with 32-fold increase in MIC were isolated by serially passaging bacterial lineages in progressively increasing concentrations of N6NH and we mainly focus on the phenotype of N6NH-resistant bacteria different from sensitive bacteria. The results showed that the resistance mechanism was attributed to synergy effect of multiple mechanisms: (i) increase biofilm formation capacity (3 ~ 4-fold); (ii) weaken the affinity of lipopolysaccharide (LPS) with N6NH (3 ~ 8-fold); and (iii) change the cell membrane permeability and potential. Interestingly, a chimeric peptide-G6, also a N6NH analog, which keep the same antibacterial activity to both wild-type and resistant clones (MIC value: 16 μg/mL), could curb N6NH-resistant mutants by stronger inhibition of biofilm formation, stronger affinity with LPS, and stronger membrane permeability and depolarization than that of N6NH.
抗生素耐药性的不断上升构成了最大的健康威胁。抗菌肽（AMPs）被认为是一种潜在有效的治疗方法。为了避免抗生素耐药性的当前危机，在临床应用之前，有必要全面了解 AMP 耐药性。在这项研究中，我们对革兰氏阴性菌肽 N6NH（21 个残基，β-折叠）在大肠杆菌 ATCC25922 中的耐药性发展进行了表征。通过在逐渐增加的 N6NH 浓度下连续传代细菌系，分离出对 N6NH 具有 32 倍 MIC 增加的 3 株 N6NH 耐药大肠杆菌突变体，我们主要关注与敏感菌不同的 N6NH 耐药菌的表型。结果表明，耐药机制归因于多种机制的协同作用：（i）增加生物膜形成能力（3 至 4 倍）；（ii）减弱脂多糖（LPS）与 N6NH 的亲和力（3 至 8 倍）；和（iii）改变细胞膜通透性和电位。有趣的是，一种嵌合肽-G6，也是 N6NH 的类似物，对野生型和耐药克隆均保持相同的抗菌活性（MIC 值：16 μg/mL），通过更强的抑制生物膜形成、更强的与 LPS 的亲和力以及更强的膜通透性和去极化作用，可抑制 N6NH 耐药突变体。
