Novel aerobic tetracycline resistance gene that chemically modifies tetracycline

Speer, Brenda S.; Salyers, Abigail A.

doi:10.1128/jb.171.1.148-153.1989

Cited by 77 publications

(39 citation statements)

References 13 publications

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“…pBS9 contains an internal segment of Tn4351 but does not cross-hybridize with IS4351 (15). When Southern blots of SalI-digested chromosomal DNA from Ms-2 were probed with 32P-labeled pBS9, a single cross-hybridizing fragment with a size of about 16 kbp was detected.…”

Section: Methodsmentioning

confidence: 99%

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Location and characterization of genes involved in binding of starch to the surface of Bacteroides thetaiotaomicron

et al. 1992

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Previous studies of starch utilization by the gram-negative anaerobe Bacteroides thetaiotaomicron have demonstrated that the starch-degrading enzymes are cell associated rather than extracellular, indicating that the first step in starch utilization is binding of the polysaccharide to the bacterial surface. Five transposongenerated mutants ofB. thetaiotaomicron which were defective in starch binding (Ms-i through Ms-5) had been isolated, but initial attempts to identify membrane proteins missing in these mutants were not successful. We report here the use of an immunological approach to identify four maltose-inducible membrane proteins, which were missing in one or more of the starch-binding mutants of B. thetaiotaomicron. Three of the maltoseinducible proteins were outer membrane proteins (115, 65, and 43 kDa), and one was a cytoplasmic membrane protein (80 kDa). The genes encoding these proteins were shown to be clustered in an 8.5-kbp segment of the B. thetaiotaomicron chromosome. Two other loci defined by transposon insertions, which appeared to contain regulatory genes, were located within 7 kbp of the cluster of membrane protein genes. The 115-kDa outer membrane protein was essential for utilization of maltoheptaose (G7), whereas loss of the other proteins affected growth on starch but not on G7. Not all of the proteins missing in the mutants were maltose regulated.We also detected two constitutively produced proteins (32 and 50 kDa) that were less prominent in all of the mutants than in the wild type. Both of these were outer membrane proteins.

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Section: Methodsmentioning

confidence: 99%

“…This fraction was ligated into the SalI site of pJRD215 (3). Tn4351 carries a gene (tetX) that confers tetracycline resistance (Tcr) on aerobically grown E. coli (15). Thus, pJRD215 clones containing Tn4351 and linked chromosomal DNA could be obtained by selection of E. coli DH5ac MCR transformants on Luria broth-tetracycline medium.…”

Section: Methodsmentioning

confidence: 99%

Location and characterization of genes involved in binding of starch to the surface of Bacteroides thetaiotaomicron

et al. 1992

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“…The reaction was terminated after all of the tetracycline had been converted to altered tetracycline by removal of the cells by centrifugation. The procedures used to ascertain that all of the tetracycline had been converted to altered tetracycline have been described previously (16). To initiate the accumulation assay, we added 2 ml of spent medium containing 0.047 mM 3H-altered tetracycline (0.071 mCi) to 8 ml of a twice-washed cell suspension.…”

Section: Methodsmentioning

confidence: 99%

“…On this basis, they classified the tetracycline resistance from Tn4400 as a new class of effluxtype resistance, TetF (9). Subsequently, our group (16) and Park and Levy (10) showed that Tn4400 also carries a gene for tetracycline modification similar to that found on Tn4351. This finding raised two questions.…”

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A tetracycline efflux gene on Bacteroides transposon Tn4400 does not contribute to tetracycline resistance

Speer

Salyers

1990

J Bacteriol

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Previously, we demonstrated that the Bacteroides transposon Tn4351, which confers tetracycline resistance only on aerobically grown Escherichia coli, carries a gene that codes for a tetracycline-inactivating enzyme (B. S. Speer and A. A. Salyers, J. Bacteriol. 170:1423-1429, 1988). However, Park et al. (B. H. Park, M. Hendricks, M. H. Malamy, F. P. Tally, and S. B. Levy, Antimicrob. Agents Chemother. 31:1739-1743, 1987) showed that E. coli carrying a closely related transposon, Tn4400, exhibits energy-dependent efflux of tetracycline as well as tetracycline-inactivating activity (B. H. Park and S. B. Levy, Antimicrob. Agents Chemother. 32:1797-1800, 1988). This result raised the question of whether efflux or inactivation or a combination of the two was necessary for resistance conferred by both transposons. We showed that cells carrying Tn4351 did not exhibit the clear-cut efflux activity seen with cells carrying Tn4400 but rather exhibited a tetracycline accumulation profile which could be explained solely on the basis of inactivation of tetracycline in the cytoplasm and rapid diffusion of altered tetracycline out of the cell. Additionally, we were able to clone the efflux and tetracycline-modifying genes of Tn4400 separately. The region carrying the efflux gene spanned one of the two regions in which Tn4400 differs from Tn4351. A clone containing the corresponding region of Tn4351 did not exhibit efflux. Thus, it appears that Tn4351 does not have the efflux gene and that efflux makes no contribution to the resistance conferred by Tn4351. The MIC for cells carrying the subclone from Tn4400 that contained only the gene for tetracycline inactivation was the same that for cells carrying both the inactivation and efflux genes. Cells carrying only the gene for tetracycline efflux were tetracycline sensitive. This was true even when the efflux gene was on a high-copy-number plasmid which increased the level of efflux to that associated with the Tcr gene on pBR328. These results indicate that efflux activity does not contribute significantly to the tetracycline resistance conferred by Tn4400.

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“…The tetX gene has been found in two closely related Bacteroides transposons, and its enzyme, TetX, requires the presence of oxygen and NADPH for activity. Ironically, TetX is functional not in Bacteroides but in aerobically grown Escherichia coli cells (30,31).…”

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Genetic Determinants of Tetracycline Resistance in Vibrio harveyi

Teo¹,

Tan

Poh³

2002

Antimicrob Agents Chemother

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Isolates of Vibrio harveyi, a prawn pathogen, have demonstrated multiple antibiotic resistance to commonly used antimicrobial agents, such as oxytetracycline. In this paper, we describe the cloning and characterization of two tetracycline resistance determinants from V. harveyi strain M3.4L. The first resistance determinant, cloned as a 4,590-bp fragment, was identical to tetA and flanking sequences encoded on transposon Tn10 from Shigella flexneri. The second determinant, cloned as a 3,358-bp fragment in pATJ1, contains two open reading frames, designated tet35 and txr. tet35 encodes a 369-amino-acid protein that was predicted to have nine transmembrane regions. It is a novel protein which has no homology to any other drug resistance protein but has low levels of homology (28%) to Na ؉ /H ؉ antiporters. Transposon mutagenesis showed that tet35 and txr were required for tetracycline resistance in a heterologous Escherichia coli host. Tetracycline accumulation studies indicate that E. coli carrying tet35 and txr can function as an energy-dependent tetracycline efflux pump but is less efficient than TetA.

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Novel aerobic tetracycline resistance gene that chemically modifies tetracycline

Cited by 77 publications

References 13 publications

Location and characterization of genes involved in binding of starch to the surface of Bacteroides thetaiotaomicron

Location and characterization of genes involved in binding of starch to the surface of Bacteroides thetaiotaomicron

A tetracycline efflux gene on Bacteroides transposon Tn4400 does not contribute to tetracycline resistance

Genetic Determinants of Tetracycline Resistance in Vibrio harveyi

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