Structural diversity of the ISCR2-mediated rolling-cycle transferable unit carrying tet(X4)

文献类型： 外文期刊

第一作者： Liu, Dejun

作者： Liu, Dejun;Shao, Dongyan;Song, Huangwei;Zhai, Weishuai;Sun, Chengtao;Zhang, Muchen;Fu, Yulin;Wu, Congming;Wang, Yang;Shen, Zhangqi;Wang, Tao;Zhang, Ying;Zhang, Rong;He, Tao;Lv, Ziquan;Ke, Yuebin;Bai, Li

作者机构：

关键词： Tet(X4); Tigecycline; ISCR2; Rolling cycle transposition

期刊名称：SCIENCE OF THE TOTAL ENVIRONMENT （ 影响因子：10.753； 五年影响因子：10.237 ）

ISSN： 0048-9697

年卷期： 2022 年 826 卷

页码：

收录情况： SCI

摘要： Background: Mobile tigecycline-resistance gene tet(X) variants have emerged as diverse pathogens fromanimal, human as well as their associated environments, which could potentially threaten public health. The insertion sequence, ISCR2, carries tet(X4) for horizontal transfer by rolling-cycle (RC) transposition. However, the diversity of ISCR2 and tet(X4) isolated from different sources is largely unknown. Methods: The tet(X4)-carrying isolates were collected from human and livestock in several multiple regions of China. The whole genomic sequences of these isolates were either obtained from NCBI GenBank or determined by Illumina Hiseq 2500 and the MinION platform. The intact transposon region, ISCR2-tet(X4)-ISCR2, observed in a small number of isolates as the reference sequence to construct the transposon phylogeny. The diversity of the genetic environments of all ISCR2-tet(X4) elements were analyzed. Results: A 2760-bp element encompassing the tet(X4)-hydrolase-encoding gene, catD, located between two ISCR2 elements was highly conserved in all isolates and could form an RC transposable unit (RC-TU). ISCR2 could also capture more resistance genes and formed a larger RC-TU base on RC transposition. However, the ISCR2-mediated RC-TUs were constantly truncated and inserted by other IS elements, indicating frequent recombination events. Of these elements, IS26 disrupted both the upstream and downstream ISCR2-mediated RC-TUs, indicating that IS26 captured tet (X4), thus leading to a wider spread of tet(X4). Conclusions: These results confirmed the critical role of ISCR2 for dissemination and co-transmission of tet(X4) and other resistance genes. More effort is needed to monitor the variation tendencies of tet(X4)-carrying mobile elements and determine the driving factors for disseminating transferable tigecycline resistance.

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