ISEcp1-mediated transposition of qnrB-like gene in Escherichia coli

Abstract

A novel QnrB-like plasmid-mediated resistance determinant, QnrB19, was identified from an Escherichia coli clinical isolate from Colombia. Its gene was associated with an ISEcp1-like insertion element that did not act as a promoter for its expression. Using an in vitro model of transposition, we showed that the ISEcp1-like element was able to mobilize the qnrB19 gene.

FIG. 1.

Schematic map of the structure of transposon Tn2012 identified on the pR4525 natural plasmid of E. coli R4525. Open reading frames are shown as arrows or horizontal boxes with an arrow indicating the orientation of the coding sequence with the gene name above the corresponding boxes. The IRL, IRR1, and IRR2 motifs are indicated (blackened bp are identical, whereas whitened bp are different), and target site duplications (ATCAA) are represented by black bars.

FIG. 2.

Nucleotide sequence of the upstream region of the qnrB19 gene. The −35 and −10 promoter elements are indicated, and the transcription start site is represented by an arrow. The former start codon corresponds to the first ATG that was initially proposed for QnrB1 (226 amino acids) (11, 12).