Genetic Characterization of Plasmid-Associated Triphenylmethane Reductase in Listeria monocytogenes
Genetic Characterization of Plasmid-Associated Triphenylmethane Reductase in Listeria monocytogenes
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DOI：
10.1128/aem.01398-14
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发表时间：
2014-09-01
影响因子：
4.4
通讯作者：
Kathariou, Sophia
中科院分区：
文献类型：
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作者：
Dutta, Vikrant;Elhanafi, Driss;Kathariou, Sophia
三苯甲烷还原酶（TMR）将有毒的三苯甲烷染料还原成无色、无毒的衍生物，产生TMR的微生物已被提议作为生物修复工具。对单核细胞增生李斯特菌H7858（1998-1999年热狗爆发）的基因组分析表明，该菌株的质粒（pLM 80）含有一个基因盒（bcrABC），赋予苯扎氯铵（BC）和其他季铵消毒剂的抗性，也含有一个基因（tmr），与来自不同革兰氏阴性菌的TMR编码基因高度同源。pLM 80相关的tmr位于bcrABC下游两个基因，作为推定的IS 1216复合转座子的一部分。为了证实tmr在三苯甲烷染料解毒中的作用，我们在来自与H7858相同爆发的菌株H7550的pLM 80-治愈衍生物中引入了pLM 80的各种tmr-携带片段，并评估了构建体对三苯甲烷染料结晶紫（CV）和孔雀石绿绿色的抗性。转录和亚克隆数据表明，TMR的调控是复杂的。包含跨越bcrABC和TMR的片段的构建体是CV抗性的，并且在这样的构建体中，TMR转录由亚致死水平的BC或CV诱导。然而，仅含有tmr及其上游基因间区域的构建体也可以赋予对CV的抗性，尽管水平较低。筛选一组抗BC的L.单核细胞增生菌株显示，所有携带bcrABC和相邻pLM 80序列的菌株，包括tmr，对CV具有抗性，并使该染料脱色。研究结果表明，TMR作为一个以前未知的适应性属性的环境持久性L的潜在作用。单核细胞增多症。
The enzyme triphenylmethane reductase (TMR) reduces toxic triphenylmethane dyes into colorless, nontoxic derivatives, and TMR-producing microorganisms have been proposed as bioremediation tools. Analysis of the genome of Listeria monocytogenes H7858 (1998-1999 hot dog outbreak) revealed that the plasmid (pLM80) of this strain harboring a gene cassette (bcrABC) conferring resistance to benzalkonium chloride (BC) and other quaternary ammonium disinfectants also harbored a gene (tmr) highly homologous to TMR-encoding genes from diverse Gram-negative bacteria. The pLM80-associated tmr was located two genes downstream of bcrABC as part of a putative IS1216 composite transposon. To confirm the role of tmr in triphenylmethane dye detoxification, we introduced various tmr-harboring fragments of pLM80 in a pLM80-cured derivative of strain H7550, from the same outbreak as H7858, and assessed the resistance of the constructs to the triphenylmethane dyes crystal violet (CV) and malachite green. Transcriptional and subcloning data suggest that the regulation of TMR is complex. Constructs harboring fragments spanning bcrABC and tmr were CV resistant, and in such constructs tmr transcription was induced by sublethal levels of either BC or CV. However, constructs harboring only tmr and its upstream intergenic region could also confer resistance to CV, albeit at lower levels. Screening a panel of BC-resistant L. monocytogenes strains revealed that all those harboring bcrABC and adjacent pLM80 sequences, including tmr, were resistant to CV and decolorized this dye. The findings suggest a potential role of TMR as a previously unknown adaptive attribute for environmental persistence of L. monocytogenes.