PDF(Pubmed)
Abstract：
In the worldwide health threat posed by antibiotic-resistant bacterial pathogens, mobile genetic elements (MGEs) play a critical role in favoring the dissemination of resistance genes. Among them, the genomic island GIsul2 and the ISCR-related element CR2-sul2 unit are believed to participate in this dissemination. However, the mobility of the two elements has not yet been demonstrated. Here, we found that the GIsul2 and CR2-sul2 units can excise from the host chromosomal attachment site (attB) in Shigella flexneri. Through establishing a two-plasmid mobilization system composed of a donor plasmid bearing the GIsul2 and a trap plasmid harboring the attB in recA-deficient Escherichia coli, we reveal that the integrase of GIsul2 can perform the excision and integration of GIsul2 and CR2-sul2 unit by site-specific recombination between att core sites. Furthermore, we demonstrate that the integrase and the att sites are required for mobility through knockout experiments. Our findings provide the first experimental characterization of the mobility of GIsul2 and CR2-sul2 units mediated by integrase. They also suggest a potential and unappreciated role of the GIsul2 integrase family in the dissemination of CR2-sul2 units carrying various resistance determinants in between.
摘要：
在抗生素耐药性细菌病原体构成的全球健康威胁中，移动遗传元件（MGEs）在促进抗性基因的传播中起着至关重要的作用。其中,基因组岛GIsul2和ISCR相关元件CR2-sul2单位被认为参与了这种传播。然而,这两个要素的流动性尚未得到证明。这里,我们发现GIsul2和CR2-sul2单元可以从福氏志贺氏菌的宿主染色体附着位点（attB）切除。通过在recA缺陷型大肠杆菌中建立由带有GIsul2的供体质粒和带有attB的陷阱质粒组成的双质粒动员系统，我们揭示了GIsul2的整合酶可以通过att核心位点之间的位点特异性重组来进行GIsul2和CR2-sul2单元的切除和整合。此外，我们通过敲除实验证明整合酶和att位点是迁移率所必需的。我们的发现为整合酶介导的GIsul2和CR2-sul2单元的迁移率提供了第一个实验表征。他们还提出了GIsul2整合酶家族在CR2-sul2单元之间携带各种抗性决定子的传播中的潜在和未被重视的作用。
