InterPro domain: IPR036271

This entry represents the C-terminal domain found in a number of different TetR transcription regulator proteins. TetR regulates the expression of the membrane-associated tetracycline resistance protein, TetA, which exports the tetracycline antibiotic out of the cell before it can attach to the ribosomes and inhibit protein synthesis [ 1 ]. TetR blocks transcription from the genes encoding both TetA and TetR in the absence of antibiotic. The C-terminal domain is multi-helical and is interlocked in the homodimer with the helix-turn-helix (HTH) DNA-binding domain. Other members of the TetR family of transcriptional regulators carry this C-terminal domain. These include:

• QacR from Staphylococcus aureus, a multidrug binding protein that represses transcription of the qacA multidrug transporter gene [ 2 ]
• Ethr, a repressor from Mycobacterium tuberculosis implicated in ethionamide drug resistance [ 3 ]
• CprB, a gamma-butyrolactone autoregulator/receptor from Streptomyces coelicolor that acts as a DNA-binding protein [ 4 ]
• YcdC, a hypothetical transcriptional regulator from Escherichia coli
• YsiA, YfiR, and YxaF, hypothetical transcriptional regulators from Bacillus subtilis
• YbiH, a hypothetical transcriptional regulator from Salmonella typhimurium

1. The complex formed between Tet repressor and tetracycline-Mg2+ reveals mechanism of antibiotic resistance. J. Mol. Biol. 247, 260-80
2. Structural mechanisms of QacR induction and multidrug recognition. Science 294, 2158-63
3. Crystal structure of the TetR/CamR family repressor Mycobacterium tuberculosis EthR implicated in ethionamide resistance. J. Mol. Biol. 340, 1095-105
4. Crystal structure of a gamma-butyrolactone autoregulator receptor protein in Streptomyces coelicolor A3(2). J. Mol. Biol. 336, 409-19