Open AccessPlasmid‐encoded tetracycline resistance in Salmonella enterica subsp. enterica serovars choleraesuis and typhimurium : identification of complete and truncated Tn 1721 elements
Author(s) -
Frech Gabriele,
Schwarz Stefan
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb13648.x
Subject(s) - plasmid , salmonella enterica , transposable element , transposase , biology , tetracycline , microbiology and biotechnology , salmonella , escherichia coli , genetics , gene , bacteria , mutant , antibiotics
During routine screening of Salmonella enterica subsp., S. enterica isolates of animal origin for plasmid‐encoded tetracycline resistance, two tetracycline resistance plasmids, the 50 kbp plasmid pGFT3 of Salmonella choleraesuis and the 9.5 kbp plasmid pGFT4 of Salmonella typhimurium var. Copenhagen DT002, were detected. The respective tetracycline resistance genes ( tet ) were identified by hybridization and PCR analysis to belong to hybridization class A. Conjugation experiments identified plasmid pGFT3 as a conjugative plasmid. Molecular analysis of the tet (A) gene area and the flanking regions identified a complete Tn 1721 ‐like transposon on plasmid pGFT3 and a truncated Tn 1721 ‐like element on plasmid pGFT4. The complete Tn 1721 ‐like element was integrated into a transposase reading frame of a truncated Tn 3 transposon also located on plasmid pGFT3. The truncated Tn 1721 ‐like element of plasmid pGFT4 lacked the entire transposase part. This Tn 1721 ‐relic was integrated in an unknown reading frame which on amino acid level showed homology to the Rop protein of Escherichia coli . A model for the deletion of the transposase part was developed on the basis of the sequences present at the termini of the truncated Tn 1721 ‐like element.