4d7m

TetR(D) in complex with anhydrotetracycline and magnesium

spinqualitylabelsall models 4d7m, resolution 1.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4d7m is a 1 chain structure with sequence from Escherichia coli. This structure supersedes the now removed PDB entry 2xps. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, MG, SO4, TDC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TETR4_ECOLX] 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. Publication Abstract from PubMed Genes that render bacteria resistant to tetracycline-derived antibiotics are tightly regulated by repressors of the TetR family. In their physiologically relevant, magnesium-complexed form, tetracyclines induce allosteric rearrangements in the TetR homodimer, leading to its release from the promoter and derepression of transcription. According to earlier crystallographic work, recognition of the tetracycline-associated magnesium ion by TetR is crucial and triggers the allosteric cascade. Nevertheless, the derivative 5a,6-anhydrotetracycline, which shows an increased affinity for TetR, causes promoter release even in the absence of magnesium. To resolve this paradox, it has been proposed that metal-free 5a,6-anhydrotetracycline acts via an exceptional, conformationally different induction mode that circumvents the normal magnesium requirement. We have tested this hypothesis by determining crystal structures of TetR-5a,6-anhydrotetracycline complexes in the presence of magnesium, ethylenediaminetetraacetic acid, or high concentrations of potassium. Analysis of these three structures reveals that, irrespective of the metal, the effects of 5a,6-anhydrotetracycline binding are indistinguishable from those of canonical induction by other tetracyclines. Together with a close scrutiny of the earlier evidence of a metal-triggered mechanism, these results demonstrate that magnesium recognition per se is not a prerequisite for tetracycline repressor allostery. Tetracycline Repressor Allostery Does Not Depend on Divalent Metal Recognition.,Werten S, Dalm D, Palm GJ, Grimm CC, Hinrichs W Biochemistry. 2014 Dec 9. PMID:25432019 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tetracycline repressor protein 3D structures

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