View source for 13ct


==Crystal structure of Sulfide-responsive transcriptional repressor (SqrR) from Rhodobacter capsulatus bound to DNA==
<StructureSection load='13ct' size='340' side='right'caption='[[13ct]], [[Resolution|resolution]] 1.91&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[13ct]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Rhodobacter_capsulatus Rhodobacter capsulatus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=13CT OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=13CT 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]] 1.91&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=CSD:3-SULFINOALANINE'>CSD</scene>, <scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></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=13ct FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=13ct OCA], [https://pdbe.org/13ct PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=13ct RCSB], [https://www.ebi.ac.uk/pdbsum/13ct PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=13ct ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/D5AT91_RHOCB D5AT91_RHOCB] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Allostery enables proteins to couple environmental signals to functional outputs, yet how allosteric mechanisms diversify during evolution remains poorly understood. Here, we address this question in the ubiquitous and functionally diverse arsenic repressor (ArsR) superfamily by integrating information-theoretic bioinformatics, structural characterization of DNA recognition and NMR measurements of fast internal dynamics. We identify conserved residues that define the structural scaffold of ArsR proteins and subfamily-specific positions that encode inducer and DNA specificity. In the persulfide sensor SqrR, the crystal structure of the DNA-bound complex reveals how operator specificity is encoded by a limited set of residues, consistent with sequence-derived predictions functionally validated by in vitro transcription assays across divergent ArsR regulators. We further show that allosteric inhibition of DNA binding in SqrR occurs without large-scale conformational rearrangements and is instead associated with changes in internal dynamics, as previously observed for the zinc sensor CzrA. Together, these results support a model in which conformational entropy preserves allosteric connectivity while relaxing sequence constraints, thereby enabling functional diversification within a protein superfamily.

Evolution of allostery without shape shifting: Internal dynamics drives functional diversification of a transcriptional repressor superfamily.,Antelo GT, Rondon JJ, Villarruel Dujovne M, Pis Diez CM, Cancian PG, Sastre S, Zeida A, Radi R, Wu H, Gonzalez-Gutierrez G, Giedroc DP, Capdevila DA bioRxiv [Preprint]. 2026 May 16:2026.05.15.721447. doi: , 10.64898/2026.05.15.721447. PMID:42182359<ref>PMID:42182359</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 13ct" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Rhodobacter capsulatus]]
[[Category: Antelo GT]]
[[Category: Capdevila DA]]
[[Category: Giedroc DP]]
[[Category: Gonzalez-Gutierrez G]]