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New page: left|200px<br /><applet load="1r22" size="450" color="white" frame="true" align="right" spinBox="true" caption="1r22, resolution 2.30Å" /> '''Crystal structure of...
 
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[[Image:1r22.gif|left|200px]]<br /><applet load="1r22" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1r22, resolution 2.30&Aring;" />
'''Crystal structure of the cyanobacterial metallothionein repressor SmtB (C14S/C61S/C121S mutant) in the Zn2alpha5-form'''<br />


==Overview==
==Crystal structure of the cyanobacterial metallothionein repressor SmtB (C14S/C61S/C121S mutant) in the Zn2alpha5-form==
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.
<StructureSection load='1r22' size='340' side='right'caption='[[1r22]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[1r22]] 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=1R22 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1R22 FirstGlance]. <br>
1R22 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechococcus_sp. Synechococcus sp.] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1R22 OCA].  
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.3&#8491;</td></tr>
 
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
==Reference==
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1r22 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1r22 OCA], [https://pdbe.org/1r22 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1r22 RCSB], [https://www.ebi.ac.uk/pdbsum/1r22 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1r22 ProSAT]</span></td></tr>
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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14568530 14568530]
</table>
[[Category: Single protein]]
== Function ==
[[Category: Synechococcus sp.]]
[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>
[[Category: Chen, X.]]
== Evolutionary Conservation ==
[[Category: Eicken, C.]]
[[Image:Consurf_key_small.gif|200px|right]]
[[Category: Giedroc, D.P.]]
Check<jmol>
[[Category: Koshlap, K.M.]]
  <jmolCheckbox>
[[Category: Pennella, M.A.]]
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/r2/1r22_consurf.spt"</scriptWhenChecked>
[[Category: Sacchettini, J.C.]]
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
[[Category: VanZile, M.L.]]
    <text>to colour the structure by Evolutionary Conservation</text>
[[Category: ZN]]
  </jmolCheckbox>
[[Category: dna binding protein]]
</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=1r22 ConSurf].
[[Category: transcriptional regulation]]
<div style="clear:both"></div>
[[Category: winged hth protein]]
== References ==
[[Category: zinc]]
<references/>
 
__TOC__
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 01:12:56 2007''
</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]]
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