Department of Oncology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China.
Antimicrob Agents Chemother. 2024 Mar 6;68(3):e0123123. doi: 10.1128/aac.01231-23. Epub 2024 Jan 30.
Multidrug-resistant , a prominent family of gram-negative pathogenic bacteria, causes a wide range of severe diseases. Strains carrying the mobile colistin resistance () gene show resistance to polymyxin, the last line of defense against multidrug-resistant gram-negative bacteria. However, the transmission of is not well understood. In this study, genomes of -positive strains were obtained from the NCBI database, revealing their widespread distribution in China. We also showed that IS, a crucial factor in transmission, is capable of self-transposition. Moreover, the self-cyclization of IS is mediated by its own encoded transposase. The electrophoretic mobility shift assay experiment validated that the transposase can bind to the inverted repeats (IRs) on both ends, facilitating the cyclization of IS. Through knockout or shortening of IRs at both ends of IS, we demonstrated that the cyclization of IS is dependent on the sequences of the IRs at both ends. Simultaneously, altering the ATCG content of the bases at both ends of IS can impact the excision rate by modifying the binding ability between IRs and ISAPL1. Finally, we showed that heat-unstable nucleoid protein (HU) can inhibit IS transposition by binding to the IRs and preventing ISAPL1 binding and expression. In conclusion, the regulation of IS-self-circling is predominantly controlled by the inverted repeat (IR) sequence and the HU protein. This molecular mechanism deepens our comprehension of dissemination.
耐多药，革兰氏阴性病原菌的一个主要家族，引起广泛的严重疾病。携带移动多粘菌素耐药基因的菌株对多粘菌素产生耐药性，多粘菌素是治疗多重耐药革兰氏阴性菌的最后一道防线。然而，对的传播机制还不是很清楚。在本研究中，我们从 NCBI 数据库中获得了阳性菌株的基因组，揭示了它们在中国的广泛分布。我们还表明，在 传播中起关键作用的 IS 能够自我转位。此外，IS 的自我环化是由其自身编码的转座酶介导的。电泳迁移率变动分析实验验证了转座酶可以结合到 IS 两端的反向重复（IRs）上，促进 IS 的环化。通过敲除或缩短 IS 两端的 IRs，我们证明了 IS 的环化依赖于 IRs 两端的序列。同时，通过改变 IS 两端碱基的 ATCG 含量，可以通过改变 IRs 与 ISAPL1 之间的结合能力来影响切除率。最后，我们表明热不稳定性核蛋白（HU）可以通过结合 IRs 来抑制 IS 的转位，从而阻止 ISAPL1 的结合和表达。总之，IS 自我环化的调节主要受反向重复（IR）序列和 HU 蛋白的控制。这一分子机制加深了我们对传播的理解。
