The TetR protein primarily functions as a transcriptional repressor regulating tetracycline resistance genes, especially those that encode efflux pumps like TetA. Its main functions are:
Regulation of Efflux Genes: TetR binds to the operator region of tetracycline resistance operons, repressing the expression of genes responsible for tetracycline efflux pumps when tetracycline is absent.
Tetracycline Sensing: When tetracycline is present, it binds to TetR, causing a conformational change that reduces TetR's affinity for the operator DNA. This allows the transcription of resistance genes, enabling the production of efflux pumps to remove tetracycline from the cell.
Responsive Regulation: The system ensures resistance mechanisms are expressed only when needed, which prevents unnecessary energy expenditure.
Thus, TetR plays a crucial role in the regulation of bacterial resistance to tetracycline antibiotics.The TcR (Tetracycline Resistance) protein family includes proteins responsible for bacterial resistance to tetracycline antibiotics.
TcR proteins mainly function as part of efflux pumps or ribosomal protection mechanisms. The key functions are:
Efflux Pump (TetA, TetB, etc.): TcR proteins are part of active efflux pumps, which remove tetracycline from bacterial cells. These pumps prevent tetracycline from reaching its target (the ribosome), ensuring that protein synthesis is not inhibited. This is one of the most common mechanisms of tetracycline resistance.
Ribosomal Protection: Some TcR proteins, like Tet(M) and Tet(O), are ribosomal protection proteins (RPPs). These proteins bind to the ribosome and displace tetracycline, preventing the antibiotic from blocking protein synthesis. This allows the bacteria to continue producing proteins even in the presence of tetracycline.
Regulation of Resistance Genes: TcR genes can also regulate the expression of other resistance genes, enabling bacteria to respond to the presence of tetracycline by increasing the production of efflux pumps or ribosomal protection proteins.
In summary, TcR proteins contribute to tetracycline resistance by either actively pumping the antibiotic out of the cell or protecting the bacterial ribosome from its inhibitory effects.
References
Thaker M, Spanogiannopoulos P, Wright GD. The tetracycline resistome. Cell Mol Life Sci. 2010 Feb;67(3):419-31. doi: 10.1007/s00018-009-0172-6. Epub 2009 Oct 28. PMID: 19862477; PMCID: PMC11115633.
Souce: NovoPro 2024-09-18