2o7o

Crystal structure analysis of TetR(D) complex with doxycycline

spinqualitylabelsall models 2o7o, resolution 1.89Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2o7o is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, DXT, MG, SO4 Related: 2tct Resources: FirstGlance, OCA, RCSB, PDBsum Function [TETR4_ECOLI] TetR is the repressor of the tetracycline resistance element; its N-terminal region forms a helix-turn-helix structure and binds DNA. Binding of tetracycline to TetR reduces the repressor affinity for the tetracycline resistance gene (tetA) promoter operator sites. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Resistance to the antibiotic tetracycline (Tc) is regulated by its binding as a Tc:Mg2+ complex to the Tet Repressor protein (TetR). Tc:TetR recognition is a complex problem, with the protein and ligand each having several possible conformations and protonation states, which are difficult to elucidate by experiment alone. We used a combination of free-energy simulations and crystallographic analysis to investigate the electrostatic interactions between protein and ligand and the possible role of induced fit in Tc binding. Tc in solution was described quantum mechanically, while Tc:TetR interactions were described by a recent, high-quality molecular-mechanics model. The orientations of the amide and imidazole groups were determined experimentally by a careful analysis of Debye-Waller factors in alternate crystallographic models. The agreement with experiment for these orientations suggested that the simulations and their more detailed, thermodynamic predictions were reliable. We found that the ligand prefers an extended, zwitterionic state both in solution and in complexation with the protein. Tc is thus preorganized for binding, while the protein combines lock-and-key behavior for regions close to the ligand's amide, enolate, and ammonium groups, with an induced fit for regions close to the Mg2+ ion. These insights and the modeling techniques employed should be of interest for engineering improved TetR ligands and improved TetR proteins for gene regulation, as well as for drug design. Protonation patterns in tetracycline:tet repressor recognition: simulations and experiments.,Aleksandrov A, Proft J, Hinrichs W, Simonson T Chembiochem. 2007 Apr 16;8(6):675-85. PMID:17361981 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tetracycline repressor protein

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