Open AccessIntegron Mobilization Unit as a Source of Mobility of Antibiotic Resistance Genes
Author(s) -
Laurent Poirel,
Amélie Carrër,
Johann Pitout,
Patrice Nordmann
Publication year - 2009
Publication title -
antimicrobial agents and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.07
H-Index - 259
eISSN - 1070-6283
pISSN - 0066-4804
DOI - 10.1128/aac.00033-09
Subject(s) - integron , transposable element , biology , plasmid , enterobacter cloacae , genetics , insertion sequence , gene , transposase , microbiology and biotechnology , escherichia coli , enterobacteriaceae , genome
Antibiotic resistance genes are spread mostly through plasmids, integrons (as a form of gene cassettes), and transposons in gram-negative bacteria. We describe here a novel genetic structure, named the integron mobilization unit (IMU), that has characteristics similar to those of miniature inverted transposable elements (MITEs). Two IMUs (288 bp each) were identified from a carbapenem-resistantEnterobacter cloacae isolate that formed a composite structure encompassing a defective class 1 integron containing the carbapenem resistance genebla GES-5 . This ß-lactamase gene was located on a 7-kb IncQ-type plasmid named pCHE-A, which was sequenced completely. The plasmid pCHE-A was not self conjugative but was mobilizable, and it was successfully transferred fromE. cloacae toPseudomonas aeruginosa . The in silico analysis of the extremities of the IMU elements identified similarities with those of insertion sequence ISSod9 fromShewanella oneidensis MR-1. The mobilization of the IMU composite structure was accomplished by using the transposase activity of ISSod9 that was provided intrans . This is the first identification of MITE-type structures as a source of gene mobilization, implicating here a clinically relevant antibiotic resistance gene.