Ortañez Jericho, Degnan Patrick H
Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States.
Front Microbiol. 2024 Mar 26;15:1241582. doi: 10.3389/fmicb.2024.1241582. eCollection 2024.
The horizontal transfer of mobile genetic elements (MGEs) is an essential process determining the functional and genomic diversity of bacterial populations. MGEs facilitate the exchange of fitness determinant genes like antibiotic resistance and virulence factors. Various computational methods exist to identify potential MGEs, but confirming their ability to transfer requires additional experimental approaches. Here, we apply a transposon (Tn) mutagenesis technique for confirming mobilization without the need for targeted mutations. Using this method, we identified two MGEs, including a previously known conjugative transposon (CTn) called CTn found in and a novel CTn, CTn, identified in . In addition, Tn mutagenesis and subsequent genetic deletion enabled our characterization of a helix-turn-helix motif gene, BVU3433 which negatively regulates the conjugation efficiency of CTn . Furthermore, our transcriptomics data revealed that BVU3433 plays a crucial role in the repression of CTn genes, including genes involved in forming complete conjugation machinery [Type IV Secretion System (T4SS)]. Finally, analysis of individual strain genomes and community metagenomes identified the widespread prevalence of CTn-like elements with putative BVU3433 homologs among human gut-associated bacteria. In summary, this Tn mutagenesis mobilization method (TMMM) enables observation of transfer events and can ultimately be applied to identify a broader diversity of functional MGEs that may underly the transfer of important fitness determinants.
可移动遗传元件（MGEs）的水平转移是决定细菌群体功能和基因组多样性的重要过程。MGEs促进了诸如抗生素抗性和毒力因子等适应性决定基因的交换。存在多种计算方法来识别潜在的MGEs，但要确认它们的转移能力则需要额外的实验方法。在此，我们应用转座子（Tn）诱变技术来确认转移，而无需进行靶向突变。使用这种方法，我们鉴定出两个MGEs，包括一个在[具体出处1]中发现的名为CTn的先前已知的接合转座子（CTn）和一个在[具体出处2]中鉴定出的新型CTn，即CTn。此外，Tn诱变和随后的基因缺失使我们能够对一个螺旋-转角-螺旋基序基因BVU3433进行表征，该基因负向调节CTn的接合效率。此外，我们的转录组学数据表明，BVU3433在抑制CTn基因（包括参与形成完整接合机制的基因[IV型分泌系统（T4SS）]）中起关键作用。最后，对单个菌株基因组和群落宏基因组的分析确定了在人类肠道相关细菌中广泛存在具有假定BVU3433同源物的CTn样元件。总之，这种Tn诱变转移方法（TMMM）能够观察转移事件，最终可用于识别更广泛的功能性MGEs多样性，这些MGEs可能是重要适应性决定因素转移的基础。
