View source for 1r1t


==Crystal structure of the cyanobacterial metallothionein repressor SmtB in the apo-form==
<StructureSection load='1r1t' size='340' side='right'caption='[[1r1t]], [[Resolution|resolution]] 1.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1r1t]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechococcus_elongatus_PCC_7942_=_FACHB-805 Synechococcus elongatus PCC 7942 = FACHB-805]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R1T OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1R1T FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.7&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1r1t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1r1t OCA], [https://pdbe.org/1r1t PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1r1t RCSB], [https://www.ebi.ac.uk/pdbsum/1r1t PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1r1t ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SMTB_SYNE7 SMTB_SYNE7] Transcriptional repressor of the expression of the smtA gene. Binds two zinc ions per dimer. The complex of DNA and SmtB is dissociated by zinc ions.<ref>PMID:12146943</ref> <ref>PMID:12407207</ref> <ref>PMID:8871549</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/r1/1r1t_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1r1t ConSurf].
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== Publication Abstract from PubMed ==
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.

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<ref>PMID:14568530</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1r1t" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Synechococcus elongatus PCC 7942 = FACHB-805]]
[[Category: Chen X]]
[[Category: Eicken C]]
[[Category: Giedroc DP]]
[[Category: Koshlap KM]]
[[Category: Pennella MA]]
[[Category: Sacchettini JC]]
[[Category: VanZile ML]]