State Key Laboratory of Respiratory Disease, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
Department of Pulmonary and Critical Care Medicine, First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
J Infect Dis. 2020 Mar 16;221(Suppl 2):S229-S236. doi: 10.1093/infdis/jiz567.
This study was performed to assess the role of the histone-like nucleoid-structuring (H-NS)-like protein, carried by blaNDM-1-encoding IncX3-type plasmids, in the dissemination of IncX3 plasmids.
The blaNDM-1-encoding IncX3 plasmids were analyzed using southern blot, conjugation, and competition assays. Virulence was evaluated with a Galleria mellonella infection model. An hns-knockout IncX3 plasmid was also constructed to identify the functions of plasmid-borne H-NS-like protein in Escherichia coli.
The assasys detected blaNDM-1-encoding IncX3-type plasmids with similar fingerprint patterns in all New Delhi metallo-β-lactamase (NDM) 1-producing carbapenem-resistant Enterobacteriaceae. The IncX3 plasmid conferred a fitness advantage to E. coli J53 but had no effect on host virulence. Moreover, the transconjugation frequency of the hns-null IncX3 plasmid pHN330-△hns was increased by 2.5-fold compared with the wild type. This was caused by up-regulation of conjugation-related plasmid-borne genes and the partition-related gene, in the J330-pHN330-△hns strain. In addition, decreased virulence was detected with this variant.
Our results highlight the important role of IncX3 plasmids in the dissemination of blaNDM-1 in south China. Plasmid-encoded H-NS-like protein can inhibit plasmid conjugation, partition, and the expression of related genes, in addition to promoting virulence in the host.
本研究旨在评估由 blaNDM-1 编码的 IncX3 型质粒携带的组蛋白样核小体结构（H-NS）样蛋白在 IncX3 质粒传播中的作用。
采用Southern blot、接合和竞争试验分析 blaNDM-1 编码的 IncX3 质粒。利用大蜡螟感染模型评估毒力。还构建了 hns 敲除 IncX3 质粒，以确定质粒携带的 H-NS 样蛋白在大肠杆菌中的功能。
该检测发现，所有携带新德里金属β-内酰胺酶（NDM）1 的耐碳青霉烯肠杆菌科中均存在 blaNDM-1 编码的 IncX3 型质粒，且指纹图谱相似。IncX3 质粒赋予大肠杆菌 J53 适应性优势，但对宿主毒力没有影响。此外，与野生型相比，hns 缺失的 IncX3 质粒 pHN330-△hns 的转导频率增加了 2.5 倍。这是由于 J330-pHN330-△hns 菌株中与接合相关的质粒携带基因和分区相关基因的上调所致。此外，还检测到该变体的毒力降低。
我们的研究结果强调了 IncX3 质粒在华南地区 blaNDM-1 传播中的重要作用。质粒编码的 H-NS 样蛋白可抑制质粒接合、分区和相关基因的表达，同时促进宿主的毒力。
