Tn5045, a novel integron-containing antibiotic and chromate resistance transposon isolated from a permafrost bacterium

A novel antibiotic and chromate resistance transposon, Tn5045, was isolated from a permafrost strain of Pseudomonas sp. Tn5045 is a compound tra.nsposon composed of three distinct genetic elements. The backbone element is a Tn1013-like Tn3 family transposon, termed Tn1013*, that contains the tnpA and the tnpR genes, encoding the transposase and resolvase, respectively, the, res-site and four genes (orfA, B, C, D) :elated to different house-keeping genes. The second element is class 1 integron, termed InC*, which is inserted into the Tn1013* res-region and contains 5'-CS-located integrase, 3'-CS-located qacE Delta 1 and sulfonamide resistance sull genes, and a single cassette encoding the streptomycin resistance anc/A2-gene. The third element is a TnOtChr-like Tn3 family transposon termed TnOtChr*, which is inserted into the transposition module of the integron and contains genes of chromate resistance (chrB, A, C, F). Tn5045 is the first example of an ancient integron-containing mobile element and also the first characterized compound transposon coding for both antibiotic and chromate, resistance. Our data demonstrate that antibiotic and chromate resistance genes were distributed in environmental bacteria independently of human activities and provide important insights into the origin and evolution of antibiotic resistance integrons. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.