1r1v
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(New page: 200px<br /><applet load="1r1v" size="450" color="white" frame="true" align="right" spinBox="true" caption="1r1v, resolution 2.3Å" /> '''Crystal structure of ...)
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Revision as of 19:49, 24 November 2007
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Crystal structure of the metal-sensing transcriptional repressor CzrA from Staphylococcus aureus in the Zn2-form
Overview
The origin of metal ion selectivity by members of the SmtB/ArsR family of, bacterial metal-sensing transcriptional repressors and the mechanism of, negative allosteric regulation of DNA binding is poorly understood. Here, we report that two homologous zinc sensors, Staphylococcus aureus CzrA and, cyanobacterial SmtB, are "winged" helix homodimeric DNA-binding proteins, that bind Zn(II) to a pair of tetrahedral, interhelical binding sites, with two ligands derived from the alpha5 helix of one subunit, Asp84, O(delta1) (Asp104 in SmtB), His86 N(delta1) (His106), and two derived from, the alpha5 helix of the other, His97' N(delta1) (His117') and His100', N(epsilon2) (Glu120'). Formation of the metal chelate drives a quaternary, structural switch mediated by an intersubunit hydrogen-binding network, that originates with the non-liganding N(epsilon2) face of His97 in CzrA, (His117 in SmtB) that stabilizes a low-affinity, DNA-binding conformation., The structure of the Zn(1) SmtB homodimer shows that both metal-binding, sites of the dimer must be occupied for the quaternary structural switch, to occur. Thus, a critical zinc-ligating histidine residue obligatorily, couples formation of the metal-sensing coordination chelate to changes in, the conformation and dynamics of the putative DNA-binding helices.
About this Structure
1R1V is a Single protein structure of sequence from Staphylococcus aureus with ZN as ligand. Full crystallographic information is available from OCA.
Reference
A metal-ligand-mediated intersubunit allosteric switch in related SmtB/ArsR zinc sensor proteins., Eicken C, Pennella MA, Chen X, Koshlap KM, VanZile ML, Sacchettini JC, Giedroc DP, J Mol Biol. 2003 Oct 31;333(4):683-95. PMID:14568530
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