AUTHOR=He Yu-Zhang , Long Teng-Fei , He Bing , Li Xing-Ping , Li Gong , Chen Liang , Liao Xiao-Ping , Liu Ya-Hong , Sun Jian 

TITLE=ISEc69-Mediated Mobilization of the Colistin Resistance Gene mcr-2 in Escherichia coli

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.564973

DOI=10.3389/fmicb.2020.564973

ISSN=1664-302X

ABSTRACT=<sec><title>Objectives</title><p>The emergence of mobile colistin resistance genes has compromised the efficacy of the last resort antibiotic, colistin, in clinical treatment. The <italic>mcr-2</italic> gene was first identified in Belgium in association with the insertion sequence IS<italic>Ec69</italic>. However, the molecular mechanisms of <italic>mcr-2</italic> mobilization are not well understood.</p></sec><sec><title>Methods</title><p>To further explore the mobilization of <italic>mcr-2</italic> gene via IS<italic>Ec69</italic>, we constructed a conjugative plasmid that carries an intact composite transposon Tn7052. Transposition assays were performed by conjugation, the transposition sites were characterized by arbitrary primed PCR and DNA sequencing.</p></sec><sec><title>Results</title><p>In this study, we experimentally demonstrated that <italic>mcr-2</italic> could be mobilized as a composite transposon Tn7052 and its transposition generated 8-bp AT-rich duplications in the host genome.</p></sec><sec><title>Conclusion</title><p>These results indicate that <italic>mcr-2</italic> gene could be mobilized by IS<italic>Ec69</italic>, the current investigations provide mechanistic insights in the transposition of <italic>mcr-2</italic>.</p></sec>