Biophysical and structural characterization of a zinc-responsive repressor of the MarR superfamily

Published on 2019-02-12T18:34:35Z (GMT) by
<div><p>The uptake of zinc, which is vital in trace amounts, is tightly controlled in bacteria. For this control, bacteria of the <i>Streptococcaceae</i> group use a Zn(II)-binding repressor named ZitR in lactococci and AdcR in streptococci, while other bacteria use a Zur protein of the Ferric uptake regulator (Fur) superfamily. ZitR and AdcR proteins, characterized by a winged helix-turn-helix DNA-binding domain, belong to the multiple antibiotic resistance (MarR) superfamily, where they form a specific group of metallo-regulators. Here, one such Zn(II)-responsive repressor, ZitR of <i>Lactococcus lactis</i> subspecies <i>cremoris</i> strain MG1363, is characterized. Size Exclusion Chromatography-coupled to Multi Angle Light Scattering, Circular Dichroism and Isothermal Titration Calorimetry show that purified ZitR is a stable dimer complexed to Zn(II), which is able to bind its two palindromic operator sites on DNA fragments. The crystal structure of ZitR holo-form (Zn(II)<sub>4</sub>-ZitR<sub>2</sub>), has been determined at 2.8 Å resolution. ZitR is the fourth member of the MarR metallo-regulator subgroup whose structure has been determined. The folding of ZitR/AdcR metallo-proteins is highly conserved between both subspecies (<i>cremoris</i> or <i>lactis</i>) in the <i>Lactococcus lactis</i> species and between species (<i>Lactococcus lactis</i> and <i>Streptococcus pneumoniae or pyogenes</i>) in the <i>Streptococcaceae</i> group. It is also similar to the folding of other MarR members, especially in the DNA-binding domain. Our study contributes to better understand the biochemical and structural properties of metallo-regulators in the MarR superfamily.</p></div>

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Varela, Paloma Fernández; Velours, Christophe; Aumont-Niçaise, Magali; Pineau, Blandine; Legrand, Pierre; Poquet, Isabelle (2019): Biophysical and structural characterization of a zinc-responsive repressor of the MarR superfamily. PLOS ONE. Collection.