移动元件ISEcp1介导bla_(CTX-M)转座机制的分析研究

The research of transposition mechanism of bla_(CTX-M) by ISEcp1

目的探索ISEcp1转座单元的类型及其转座机制。方法采用BLAST比对分析GenBank库中ISEcp1及其下游blaCTX-M所处的基因环境。通过ResFinder预测耐药基因,BLASTN/BLASTP等对ORF和假基因进行核实与信息完善,并利用ISfinder对移动元件进行精细注释,最后运用Inkscape 0.48.1绘图。结果blaCTX-M常位于移动元件ISEcp1下游,二者可形成完整的转座单元,该转座单元主要可分为6类,即:ISEcp1-blaCTX-M-Δorf477转座单元、ISEcp1-blaCTX-M-IS903-ΔiroN转座单元、ISEcp1-blaCTX-M转座单元、ISEcp1-blaCTX-M-orf3转座单元、ISEcp1-blaCTX-M-orfX转座单元和ISEcp1-blaCTX-M-ΔIS26-orf222转座单元。ISEcp1中的P1为强启动子,调控下游blaCTX-M的表达。结论 ISEcp1可通过捕获不同的基因形成相应的转座单元,这些转座单元在blaCTX-M的传播和表达的过程中起重要作用。

Objective To analyze the types and transposition mechanisms of the IS Ecp1-mediated transposition units.Methods BLAST was used to analyze the sequences harboring IS Ecp1 and bla CTX-M submitted to GenBank.Annotations of resistance genes and mobile elements were carried out using ResFinder and ISfinder.Open reading frames and pseudogenes were validated using BLASTP/BLASTN searches.Gene organization diagrams were drawn in Inkscape 0.48.1.Results bla CTX-M was often located downstream of IS Ecp1,forming a complete transposition unit.The transposition units could be mainly divided into 6 types,namely IS Ecp1-bla CTX-M-Δorf477 transposition unit,IS Ecp1-bla CTX-M-IS903-ΔiroN transposition unit,IS Ecp1-bla CTX-M transposition unit,IS Ecp1-bla CTX-M-orf3 transposition unit,IS Ecp1-bla CTX-M-orfX transposition unit and IS Ecp1-bla CTX-M-ΔIS26-orf222 transposition unit.P1 within IS Ecp1 was a strong promoter which regulated the expression of bla CTX-M.Conclusion IS Ecp1 can form corresponding transposition units by capturing different genes.These transposition units play an important role in the transformation and expression of bla CTX-M.