Skip to Content
Merck
  • Tetracycline repressor allostery does not depend on divalent metal recognition.

Tetracycline repressor allostery does not depend on divalent metal recognition.

Biochemistry (2014-11-29)
Sebastiaan Werten, Daniela Dalm, Gottfried Julius Palm, Christopher Cornelius Grimm, Winfried Hinrichs
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Magnesium, in a Sure/Seal bottle, turnings, 37.5 mmol
Sigma-Aldrich
Magnesium, in a Sure/Seal bottle, turnings, anhydrous tetrahydrofuran 37.5 mmol
Sigma-Aldrich
Magnesium, wire, 127 μm diameter, 99.9% trace metals basis
Sigma-Aldrich
Magnesium, rod, diam. 6 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Magnesium, 20-230 mesh, reagent grade, 98%
Sigma-Aldrich
Magnesium, chips, 6-35 mesh, 99.98% trace metals basis
Sigma-Aldrich
Magnesium preparation, Highly Reactive Rieke® Metal, suspension, 2.5 g in THF
Sigma-Aldrich
Magnesium, ReagentPlus®, powder, −325 mesh, 99.5% trace metals basis
Sigma-Aldrich
Magnesium, ReagentPlus®, ribbon, ≥99% trace metals basis
Sigma-Aldrich
Magnesium, ribbon, ≥99.0% Mg basis
Sigma-Aldrich
Magnesium, purum, for Grignard reactions, ≥99.5%, turnings
Sigma-Aldrich
Magnesium, powder, ≥99%
Sigma-Aldrich
Magnesium, grit, ≥99.0% (KT)
Sigma-Aldrich
Magnesium, dendritic pieces, purified by distillation, 99.998% trace metals basis
Sigma-Aldrich
Magnesium, turnings, reagent grade, 98%
Sigma-Aldrich
Magnesium, ReagentPlus®, powder, −50 mesh, ≥99%
Sigma-Aldrich
Magnesium, turnings, 5-25 mm, 99.95% trace metals basis
Magnesium, wire reel, 0.1m, diameter 0.4mm, as drawn, 99.9+%
Magnesium, wire reel, 1m, diameter 1.1mm, as drawn, 99.9+%
Magnesium, wire reel, 2m, diameter 0.125mm, as drawn, 99.9+%
Magnesium, microfoil, 25x25mm, thinness 1.0μm, specific density 174μg/cm2, 6 micron aluminum permanent support, 99.9%
Magnesium, wire reel, 0.1m, diameter 1.0mm, as drawn, 99.9+%
Magnesium, wire reel, 0.5m, diameter 0.125mm, as drawn, 99.9+%
Magnesium, wire reel, 0.1m, diameter 0.5mm, as drawn, 99.9+%
Magnesium, wire reel, 1m, diameter 1.0mm, as drawn, 99.9+%
Magnesium, wire reel, 0.1m, diameter 1.1mm, as drawn, 99.9+%
Magnesium, wire reel, 0.5m, diameter 0.25mm, as drawn, 99.9+%
Magnesium, wire reel, 2m, diameter 0.4mm, as drawn, 99.9+%
Magnesium, wire reel, 0.5m, diameter 0.4mm, as drawn, 99.9+%
Magnesium, wire reel, 2m, diameter 0.5mm, as drawn, 99.9+%