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].
• Screens were designed based upon fusions with three antibiotic induced promoters: the tetracycline induced tetA/tetR promoter from transposon Tn10, the erythromycin induced promoter from the Staphylococcus aureus ermC erythromycin-resistance gene and the chloramphenicol induced promoter from the S. aureus cat86 chloramphenicol-resistance gene [2].
• 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 [3].
• Some sequence elements in this novel membrane protein share similarity to regions in the transposon Tn10-encoded tetracycline resistance determinant TetA, the multidrug transporter Bmr from Bacillus subtilis, and the bicyclomycin resistance determinant Bcr from E. coli [4].
• Hydrophilicity plots of BaiG show a high degree of similarity to class K and L TetA proteins from gram-positive bacteria, and, like these classes of TetA proteins, BaiG has 14 proposed transmembrane domains [5].

High impact information on tetA

• Differential regulation of the Tn10-encoded tetracycline resistance genes tetA and tetR by the tandem tet operators O1 and O2 [6].
• The results demonstrate that expression of the resistance gene tetA is regulated by Tet repressor bound to either O1 or O2 [6].
• In the present studies, multimer formation was examined in mixtures of dodecylmaltoside extracts of membranes from Escherichia coli cells containing different TetA derivatives [7].
• Based on hydrophobicity profiles, we identified 12 potential transmembrane segments in TetA [8].
• Membrane topology of the pBR322 tetracycline resistance protein. TetA-PhoA gene fusions and implications for the mechanism of TetA membrane insertion [8].

Chemical compound and disease context of tetA

• The effect of novobiocin, a gyrase inhibitor, and of catabolite repression on the expression of different classes of tetA genes in Escherichia coli was studied [9].
• 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 [10].

Biological context of tetA

• Point mutations in either tetA or tetB led to the defective expression of the resistance mechanism involving tetracycline efflux [11].
• The deduced amino acid sequence of the class E TetA protein shows 50 to 56% identity with the sequences of five related TetA proteins (classes A through D and G) [12].
• The sequence affects recombination between tandem repeats within the tetA but not the bla gene of pBR322 [13].
• However, in the interdomain loop of 11 of 14 homologous TetA efflux proteins, computational analysis revealed a short alpha-helix, which includes some residues affecting activity and substrate specificity [14].
• Structure and function of the class C tetracycline/H+ antiporter: three independent groups of phenotypes are conferred by TetA (C) [15].

Anatomical context of tetA

• For this to occur on a plasmid, we have shown that the transcribing RNA polymerase must be anchored to the cell membrane by transcription, translation, and export of the tetA gene and that the cell background must be topA [16].
• Spheroplasts and inside-out vesicles of the TetA protein synthesizing maxicells were subjected to limited digestion by proteases of different specificities [17].

Associations of tetA with chemical compounds

• The tetracycline resistance determinant in transposon Tn10 consists of two genes, the tetA resistance gene and the tetR repressor gene, that are transcribed from divergent overlapping promoters [18].
• Addition of the inducer 5a,6-anhydrotetracycline results in a 270- to 430-fold increase in tetA mRNA and a 35- to 65-fold increase in tetR mRNA [18].
• An aspartate residue in the 8-9 loop that has no counterpart in LacY and TetA, but is conserved among members of the aromatic acid/H(+) symporter family of the MFS, was found to be critical for 4-HBA transport [19].
• We found that, when chelated to tetracycline, Fe(2+) cleaved the backbone of TetA predominantly at a single position, glutamine 225 in transmembrane helix 7 [20].
• Since alpha-methylglucoside transport was not affected, the overproduced TetA protein may cause not destruction of membrane structure but rather unrestricted translocation of protons and/or ions across the membrane [21].

Analytical, diagnostic and therapeutic context of tetA

• TetA, a tetracycline cation/proton antiporter, was expressed in Escherichia coli with a C-terminal tag of six histidines, solubilized in dodecyl maltoside and purified in a single step using Ni2+ affinity chromatography [22].

References