The X-ray crystal structure analysis of inducer-free Tet repressor, TetR, at 2.4 A resolution identifies one of two openings of the tunnel-like binding site as the entrance for the inducer tetracycline-Mg2+, [Mg Tc]+. Recognition and binding of the inducer unleashes conformational changes leading to the induced state of TetR ...
The X-ray crystal structure analysis of inducer-free Tet repressor, TetR, at 2.4 A resolution identifies one of two openings of the tunnel-like binding site as the entrance for the inducer tetracycline-Mg2+, [Mg Tc]+. Recognition and binding of the inducer unleashes conformational changes leading to the induced state of TetR. In the first step, the C-terminal turn of alpha-helix 6 unwinds, thereby altering the orientation of alpha-helix 4. This different orientation of alpha-helix 4 is stabilized by a series of hydrogen bonds mediated through a chain of eight water molecules. The alpha-helix 4 connects the DNA-binding domain (alpha-helices 1 to 3) to the rigid TetR core, and thus regulates gene expression through its respective orientations.
Related Citations:
The Complex Formed between Tet Repressor and Tetracycline-Mg2+ Reveals Mechanism of Antibiotic Resistance Kisker, C., Hinrichs, W., Tovar, K., Hillen, W., Saenger, W. (1995) J Mol Biol 247: 260
Structure of the Tet Repressor-Tetracycline Complex and Regulation of Antibiotic Resistance Hinrichs, W., Kisker, C., Duvel, M., Muller, A., Tovar, K., Hillen, W., Saenger, W. (1994) Science 264: 418
Organizational Affiliation:
Institut für Kristallographie, Freie Universität Berlin, Germany.
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