PDF(Pubmed)
Abstract：
The blaNDM-1 gene and its variants encode metallo-beta-lactamases that confer resistance to almost all beta-lactam antibiotics. Genes encoding blaNDM-1 and its variants can be found in several Acinetobacter species, and they are usually linked to two different plasmid clades. The plasmids in one of these clades contain a gene encoding a Rep protein of the Rep_3 superfamily. The other clade consists of medium-sized plasmids in which the gene (s) involved in plasmid replication initiation (rep)have not yet been identified. In the present study, we identified the minimal replication region of a blaNDM-1-carrying plasmid of Acinetobacter haemolyticus AN54 (pAhaeAN54e), a member of this second clade. This region of 834 paired bases encodes three small peptides, all of which have roles in plasmid maintenance. The plasmids containing this minimal replication region are closely related; almost all contain blaNDM genes, and they are found in multiple Acinetobacter species, including A. baumannii. None of these plasmids contain an annotated Rep gene, suggesting that their replication relies on the minimal replication region that they share with the plasmid pAhaeAN54e. These observations suggest that this plasmid lineage plays a crucial role in the dissemination of the blaNDM-1 gene and its variants.
摘要：
blaNDM-1基因及其变体编码金属-β-内酰胺酶,其赋予对几乎所有β-内酰胺抗生素的抗性。编码blaNDM-1及其变体的基因可以在几种不动杆菌属中发现，它们通常与两个不同的质粒进化枝连接。这些进化枝之一中的质粒含有编码Rep_3超家族的Rep蛋白的基因。另一个进化枝由中等大小的质粒组成,其中涉及质粒复制起始(rep)的基因尚未被鉴定。在本研究中,我们确定了携带blaNDM-1的溶血不动杆菌AN54质粒（pAhaeAN54e）的最小复制区，第二个进化枝的成员。该区域的834个配对碱基编码三个小肽，所有这些都在质粒维持中发挥作用。含有这个最小复制区的质粒密切相关；几乎所有的质粒都含有blaNDM基因，它们存在于多种不动杆菌属物种中，包括A.baumannii.这些质粒都不包含注释的Rep基因，这表明它们的复制依赖于它们与质粒pAhaeAN54e共有的最小复制区。这些观察结果表明，该质粒谱系在blaNDM-1基因及其变体的传播中起着至关重要的作用。
