【摘要】 目的插入序列IS6100与耐药基因转移密切相关,本研究旨在初步探究IS6100转移DNA序列的机制。方法以Genbank库中已有序列中含两个及两个以上拷贝IS6100序列的质粒或者染色体为研究对象,通过生物信息分析的方法分析各IS6100侧翼的靶位点重复序列(TSD),推测该元件转座酶可能的工作机制。结果共检索到22条序列,含5条染色体、16条质粒以及1条定位未知的转座子序列。其中有13条序列(59%)来自鞘脂菌属细菌,余下均来自条件致病菌的染色体或质粒。在鞘脂菌属细菌TKS中,IS6100拷贝数可多达29个,且IS6100和鞘脂菌属细菌基因组的GC%均接近60%。共有35条不同的8bpTSD在这些菌株中出现的频率为2~8次。TSD的GC%含量在13%~100%,有87%(30/35)的TSD序列GC%含量均≥50%。这些TSD可同时出现在同一菌株的染色体或质粒内部、同一菌株的染色体和质粒之间、不同菌株的染色体和质粒间。结论 IS6100的产生菌可能为鞘脂菌属细菌。IS6100的作用靶位点没有高度选择性,但仍倾向作用于高GC%含量位点。两个IS6100可以形成复合转座子,转移其间的DNA序列,这些转座事件可以发生在分子间和分子内。更多还原

【Abstract】 Objective The insertion element IS6100 is closely related to antibiotic resistance transfer in bacteria. Here we aim to explore the possible origin of IS6100 and its mechanism of horizontal transfer of DNA fragments.Methods Taking the plasmid or chromosome DNA containing two or more copies of the IS6100 element in the GenBank library as the research object, the target site duplication(TSD) flanking each IS6100 was analyzed by bioinformatics tools, and the potential mechanism of the transposase encoded by IS6100 is speculated.Results A total of 22 DNA sequences including 5 chromosome, 16 plasmid sequences, and a transposon sequence of unknown location were founded. Among them, 13 sequences(59%) were from DNA of Sphingobium sp., and the rest were from chromosomes or plasmids of conditional pathogens. In Sphingobium sp. strain TKS, the copy number of IS6100 was as many as 29, and the GC%content of the IS6100 or genome was close to 60%. Thirty-five different 8 bp TSDs were present in these strains with a frequency of2-8. The GC% content of TSD was between 13% and 100%, and the GC% content in 87%(30/35) TSD sequences was ≥ 50%.These TSDs occurred simultaneously in the chromosome and/or plasmid of the same strain or different strains.Conclusion IS6100 may originated from strains of Sphingobium sp.. IS6100 has no high selectivity for its target site, but still tends to act on high GC% sites. Two IS6100 s can form a composite transposon and transfer a DNA sequence between them, and these transposition events can occur intermolecularly and intramolecularly.更多还原