Molecular characterization of the class II multiresistance transposable element Tn1403 from Pseudomonas aeruginosa

Abstract

Transposon Tn1403 is a 19.9-kb multiresistance class II transposable element originally found on the RPL11 plasmid from a clinical isolate of Pseudomonas aeruginosa. It encodes resistance to ampicillin (PSE-1 beta-lactamase), streptomycin and spectinomycin (aadA and aphC), and chloramphenicol (cat). It has structural homology with the tnpM and tnpI sequences of Tn21 and inverted repeats and res and tnpR sequences of Tn501, but it has no structural homology nor functional complementation with the resolvase gene of Tn21 or Tn3. Sequence analysis revealed long inverted repeats at each extremity of Tn1403 containing 38-bp inverted repeats that were 97.4% similar to those of Tn1721 and 5-bp direct repeats. Transposition assays showed a low frequency of transposition (3.5 x 10(-6)) compared with that of Tn3 (3.3 x 10(-3)) and no resolution of cointegrates.

Integrons found in different locations have identical 5' ends but variable 3' ends

“…In all cases, the sequences are identical up to the previously identified outer end of the 5'-conserved segment (14) and diverge immediately after this point. The sequence of this region from Tn1403 has recently been published (41) and diverges at the same point (Fig. 3).…”

“…(6) and found at the 5' ends of integrons (13) is shown in boldface. Sequences were previously published for Tn2l (12,18), R46 (14), and Tnl403 (41). The (31) with corrections.…”

Family of Class 1 Integrons Related to In4 from Tn 1696

“…The most recent published map indicates the presence of blaP1 (PSE-1), cat, aadA, and aphC antibiotic resistance genes (53). An intI1 gene was also shown, and the IRi end of the 5Ј-CS was sequenced, but the restriction sites characteristic of the 3Ј-CS are not present, consistent with the absence of sulfonamide resistance.…”

“…Tn1403 is a transposon isolated from a clinical strain of P. aeruginosa (28,53) and confers resistance to carbenicillin, streptomycin, spectinomycin, and chloramphenicol, but not to sulfonamides. The most recent published map indicates the presence of blaP1 (PSE-1), cat, aadA, and aphC antibiotic resistance genes (53).…”

“…In28 is found within the transposon Tn1403 (28,53), which was recovered from a clinical strain of Pseudomonas aeruginosa which was isolated in the United States in 1973-1974 (26) and contains the IncP-2 plasmid RPL11. RPL11 transfers resistance to gentamicin, carbenicillin, streptomycin, tetracycline, sulfonamides, chloramphenicol, and mercury (26), while Tn1403 confers resistance to only carbenicillin, streptomycin, spectinomycin, and chloramphenicol (28,53). In1 is found in the multidrug resistance plasmid R46, originally from a Salmonella enterica var.…”