Disease relevance of tetA

• Potential silencing of the resistance genes bla(OXA-2), aadA1, sul1, and tetA carried on the plasmid pVE46 in a recent porcine isolate of Escherichia coli was investigated following oral inoculation of the strain into organic piglets [1].
• 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 [2].
• The pp-tet was highly homologous to the tet(D) of plasmid RA1 isolated from Aeromonas hydrophila with two nucleotide differences in the tetR, and of plasmid pIP173 from Salmonella ordonez with two nucleotide differences in the tetA [3].
• The pAB124 tet determinant differed from the tetA through tetD determinants found in gram-negative bacteria in DNA-DNA hybridization and in the ability to prevent accumulation of different tetracycline derivatives, but was closely related to the tet determinant of another plasmid isolated from Bacillus species, pBC16 [4].
• The two recombinant phages are convenient delivery vehicles which permit the in vivo substitution of the tetA locus of any Tn10 insertion with the Tes or the Tek fragment [5].

High impact information on tetA

• Increased unconstrained plasmid supercoiling was achieved by inserting the tyrT promoter upstream of the tetracycline resistance gene tetA and transformation into a topA host [6].
• To determine whether microbial chemosensors can be used to find new or better biocatalysts, we constructed Escherichia coli hosts that recognize the product of a biocatalytic conversion through the transcriptional activator NahR and respond by expression of a lacZ or tetA reporter gene [7].
• Lethality of the amplified products in the presence of tetracycline is a peculiarity of the tetA gene at high gene dosage [8].
• Second-site suppressor mutations for the serine 202 to phenylalanine substitution within the interdomain loop of the tetracycline efflux protein Tet(C) [9].
• The NH2-terminal half of the Tn10-specified tetracycline efflux protein TetA contains a dimerization domain [10].

Chemical compound and disease context of tetA

• Sequence of a class E tetracycline resistance gene from Escherichia coli and comparison of related tetracycline efflux proteins [11].
• On the promoter side, the main features of the L: -arabinose inducible araBAD promoter (P(BAD)), the lac promoter, the L: -rhamnose inducible rhaP ( BAD ) promoter, the T7 RNA polymerase promoter, the trc and tac promoter, the lambda phage promoter p ( L ), and the anhydrotetracycline-inducible tetA promoter/operator are summarized [12].
• The aspartate 15 residue within the first predicted intramembrane helix of the tetracycline efflux protein Tet has been conserved in four tetracycline resistance determinants from gram-negative bacteria [13].

Biological context of tetA

• Based on the deduced amino acid sequence, the tetA proteins of RP1/Tn1721 are 78% homologous with that of pBR322 and 45% homologous with that of Tn10 [14].
• Two open reading frames of divergent polarity have been assigned to a regulatory gene (tetR) and a gene encoding a resistance protein (tetA) [14].
• We determined the nucleotide sequence of the class E tetA gene on plasmid pSL1456 from Escherichia coli SLH1456A [11].
• Complementation occurred between promoter-proximal tet point mutations and distal tet::Tn5 insertions, suggesting the existence of two structural genes, tetA and tetB [15].
• These results, together with the analysis of polypeptides in minicells harboring pDU938tet::Tn5 mutants, suggested that tetA and tetB are expressed coordinately in an operon [15].

Anatomical context of tetA

• The tetB gene encodes the previously characterized 36,000-dalton cytoplasmic membrane TET protein, but the product of tetA was not identified [15].

Associations of tetA with chemical compounds

• While the repressive effect of the TetR protein from strain C58 (TetRC58) on the tetA gene from strain RP4 (tetARP4) was not relieved by tetracycline, repression of tetAC58 by TetRRP4 was lifted by this antibiotic [16].
• In the Tet(B)-containing vesicle study, tigecycline did not significantly inhibit tetracycline efflux-coupled proton translocation and at 10 microM did not cause proton translocation [17].
• Fe(2+)-tetracycline-mediated cleavage of the Tn10 tetracycline efflux protein TetA reveals a substrate binding site near glutamine 225 in transmembrane helix 7 [18].
• The enhanced gyrase cleavage also required translation; chloramphenicol treatment or the insertion of a translation terminator within the 5'-proximal region of the tetA gene abolished the enhanced cleavage [19].
• Doxycycline was the most effective inducer of tetA gene expression [20].

Other interactions of tetA

• The direction of transcription is opposite to that of neighboring gene tetA, which encodes the TetA protein [21].
• Subcloning, transposon mutagenesis, and DNA sequence analysis revealed that this DNA fragment contained two divergently transcribed genes, tetA and tetR, encoding products that were very similar to proteins of the Tet(A) class of tetracycline resistance systems [16].
• It contains three 38-bp inverted repeats, and (in this order) a new orfI, a resolution site (res), genes encoding resolvase (tnpR), transposase (tnpA), tetracycline-resistance (TcR) repressor (tetR), TcR (tetA) and a truncated transposase gene (tnpA') [22].
• On pBR322 DNA, gyrase cleavage sites were concentrated in the region between the 3'-ends of the tetA and bla genes [19].
• The structural genes for tetA, the Tn10 tetracycline-resistance function, and for tetR, the Tn10 tet repressor, are transcribed in opposite directions from promoters in a regulatory region located between the two structural genes [23].

Analytical, diagnostic and therapeutic context of tetA

• Muliplex PCR analyses indicated that 97% of these strains contained at least 1 of 14 tetracycline resistance genes [tetA, tetB, tetC, tetD, tetE, tetG, tetK, tetL, tetM, tetO, tetS, tetA(P), tetQ, and tetX] examined [24].
• Site-directed mutagenesis of selected residues within TetA(P) was performed to elucidate their role in tetracycline efflux [25].

References