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Roy Kishony - One of the best experts on this subject based on the ideXlab platform.

Stefan Schwarz - One of the best experts on this subject based on the ideXlab platform.

  • identification of a novel trimethoprim Resistance gene dfrk in a methicillin resistant staphylococcus aureus st398 strain and its physical linkage to the Tetracycline Resistance gene tet l
    Antimicrobial Agents and Chemotherapy, 2009
    Co-Authors: Kristina Kadlec, Stefan Schwarz
    Abstract:

    A novel trimethoprim Resistance gene, designated dfrK, was detected in close proximity to the Tetracycline Resistance gene tet(L) on the ca. 40-kb plasmid pKKS2187 in a porcine methicillin (meticillin)-resistant Staphylococcus aureus isolate of sequence type 398. The dfrK gene encodes a 163-amino-acid dihydrofolate reductase that differs from all so-far-known dihydrofolate reductases.

  • diversity of Tetracycline Resistance genes in bacteria from chilean salmon farms
    Antimicrobial Agents and Chemotherapy, 2003
    Co-Authors: Claudio D Miranda, Stefan Schwarz, Corinna Kehrenberg, Catherine Ulep, Marilyn C Roberts
    Abstract:

    Twenty-five distinct Tetracycline-resistant gram-negative bacteria recovered from four Chilean fish farms with no history of recent antibiotic use were examined for the presence of Tetracycline Resistance (tet) genes. Sixty percent of the isolates carried 1 of the 22 known tet genes examined. The distribution was as follows. The tet(A) gene was found in six isolates. The tet(B) gene was found in two isolates, including the first description in the genus Brevundimonas. Two isolates carried the tet(34) and tet(B) genes, including the first description of the tet(34) gene in Pseudomonas and Serratia and the first description of the tet(B) gene in Pseudomonas. The tet(H) gene was found in two isolates, which includes the first description in the genera Moraxella and Acinetobacter. One isolate carried tet(E), and one isolate carried tet(35), the first description of the gene in the genus Stenotrophomonas. Finally, one isolate carried tet(L), found for the first time in the genus Morganella. By DNA sequence analysis, the two tet(H) genes were indistinguishable from the previously sequenced tet(H) gene from Tn5706 found in Pasteurella multocida. The Acinetobacter radioresistens isolate also harbored the Tn5706-associated 1,063-bp IS element IS1597, while the Moraxella isolate carried a 1,026-bp IS-like element whose 293-amino-acid transposase protein exhibited 69% identity and 84% similarity to the transposase protein of IS1597, suggesting the presence of a novel IS element. The distribution of tet genes from the Chilean freshwater ponds was different than those that have previously been described from other geographical locations, with 40% of the isolates carrying unidentified Tetracycline Resistance genes.

  • molecular analysis of Tetracycline Resistance in salmonella enterica subsp enterica serovars typhimurium enteritidis dublin choleraesuis hadar and saintpaul construction and application of specific gene probes
    Journal of Applied Microbiology, 2000
    Co-Authors: Gabriele Frech, Stefan Schwarz
    Abstract:

    A total of 65 epidemiologically unrelated Tetracycline-resistant isolates of the six Salmonella enterica subsp. enterica (Salm.) serovars Dublin, Choleraesuis, Typhimurium, Enteritidis, Hadar and Saintpaul were investigated for the presence of Tetracycline Resistance genes. For this, specific gene probes of the Tetracycline Resistance genes (tet) of the hybridization classes A, B, C, D, E and G were constructed by cloning PCR-amplified internal segments of the respective tet structural genes. These gene probes were sequenced and used in hybridization experiments with plasmid DNA or endonuclease digested whole cell DNA as targets. Only tet(A) genes were detected on plasmids in all Salm. Dublin isolates as well as in single isolates of Salm. Choleraesuis and Salm. Typhimurium. Genes of the hybridization classes B, C, D and G, but also in some cases those of class A, were located in the chromosomal DNA of the corresponding Salmonella isolates. Restriction fragment length polymorphisms (RFLPs) of tet gene carrying fragments were detected in chromosomally Tetracycline-resistant isolates. These RFLPs might represent valuable additional tools for the identification and characterization of Tetracycline-resistant Salmonella isolates.

  • Tetracycline Resistance in salmonella enterica subsp enterica serovar dublin
    Antimicrobial Agents and Chemotherapy, 1998
    Co-Authors: Gabriele Frech, Stefan Schwarz
    Abstract:

    The 47-kbp plasmid pGFT1 from Salmonella enterica subsp. enterica serovar Dublin mediated Tetracycline Resistance via a tet(A) gene located on an integrated copy of a Tn1721-analogous transposon. The integration site of the transposon was located within the reading frame of a fip gene. Plasmid pGFT1 was shown to be conjugative and to be able to replicate and express Tetracycline Resistance in Escherichia coli.

Leonard Amaral - One of the best experts on this subject based on the ideXlab platform.

Remy Chait - One of the best experts on this subject based on the ideXlab platform.

Christian Berens - One of the best experts on this subject based on the ideXlab platform.

  • mechanisms underlying expression of tn10 encoded Tetracycline Resistance
    Annual Review of Microbiology, 1994
    Co-Authors: Wolfgang Hillen, Christian Berens
    Abstract:

    Tetracycline-Resistance determinants encoding active efflux of the drug are widely distributed in gram-negative bacteria and unique with respect to genetic organization and regulation of expression. Each determinant consists of two genes called tetA and tetR, which are oriented with divergent polarity, and between them is a central regulatory region with overlapping promoters and operators. The amino acid sequences of the encoded proteins are 43-78% identical. The Resistance protein TetA is a Tetracycline/metal-proton antiporter located in the cytoplasmic membrane, while the regulatory protein TetR is a Tetracycline inducible repressor. TetR binds via a helix-turn-helix motif to the two tet operators, resulting in repression of both genes. A detailed model of the repressor-operator complex has been proposed on the basis of biochemical and genetic data. The tet genes are differentially regulated so that repressor synthesis can occur before the Resistance protein is expressed. This has been demonstrated for the Tn10-encoded tet genes and may be a common property of all tet determinants, as suggested by the similar locations of operators with respect to promoters. Induction is mediated by a Tetracycline-metal complex and requires only nanomolar concentrations of the drug. This is the most sensitive effector-inducible system of transcriptional regulation known to date. The crystal structure of the TetR-Tetracycline/metal complex shows the Tet repressor in the induced, non-DNA binding conformation. The structural interpretation of many noninducible TetR mutants has offered insight into the conformational changes associated with the switch between inducing and repressing structures of TetR. Tc is buried in the core of TetR, where it is held in place by multiple contacts to the protein.

  • mechanisms underlying expression of tn10 encoded Tetracycline Resistance
    Annual Review of Microbiology, 1994
    Co-Authors: Wolfgang Hillen, Christian Berens
    Abstract:

    Tetracycline-Resistance determinants encoding active efflux of the drug are widely distributed in gram-negative bacteria and unique with respect to genetic organization and regulation of expression. Each determinant consists of two genes called tetA and tetR, which are oriented with divergent polarity, and between them is a central regulatory region with overlapping promoters and operators. The amino acid sequences of the encoded proteins are 43-78%