View source for 6qjx


==TetR(D) T103A mutant in complex with minocycline and magnesium==
<StructureSection load='6qjx' size='340' side='right'caption='[[6qjx]], [[Resolution|resolution]] 2.10&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6qjx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6QJX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6QJX 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]] 2.1&#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=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=MIY:(4S,4AS,5AR,12AS)-4,7-BIS(DIMETHYLAMINO)-3,10,12,12A-TETRAHYDROXY-1,11-DIOXO-1,4,4A,5,5A,6,11,12A-OCTAHYDROTETRACENE-2-CARBOXAMIDE'>MIY</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=6qjx FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6qjx OCA], [https://pdbe.org/6qjx PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6qjx RCSB], [https://www.ebi.ac.uk/pdbsum/6qjx PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6qjx ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TETR4_ECOLX TETR4_ECOLX] TetR is the repressor of the tetracycline resistance element; its N-terminal region forms a helix-turn-helix structure and binds DNA. Binding of tetracycline to TetR reduces the repressor affinity for the tetracycline resistance gene (tetA) promoter operator sites.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Allosteric regulation of the Tet repressor (TetR) homodimer relies on tetracycline binding that abolishes the affinity for the DNA operator. Previously, interpretation of circular dichroism data called for unfolding of the alpha-helical DNA-binding domains in absence of binding to DNA or tetracycline. Our small angle X-ray scattering of TetR(D) in solution contradicts this unfolding as a physiological process. Instead, in the core domain crystal structures analyses show increased immobilisation of helix alpha9 and two C-terminal turns of helix alpha8 upon tetracycline binding. Tetracycline complexes of TetR(D) and four single-site alanine variants were characterised by isothermal titration calorimetry, fluorescence titration, X-ray crystal structures, and melting curves. Five crystal structures confirm that Thr103 is a key residue for the allosteric events of induction, with the T103A variant lacking induction by any tetracycline. The T103A variant shows anti-cooperative inducer binding, and a melting curve of the tetracycline complex different to TetR(D) and other variants. For the N82A variant inducer binding is clearly anti-cooperative but triggers the induced conformation.

Thermodynamics, cooperativity and stability of the tetracycline repressor (TetR) upon tetracycline binding.,Palm GJ, Buchholz I, Werten S, Girbardt B, Berndt L, Delcea M, Hinrichs W Biochim Biophys Acta Proteins Proteom. 2020 Feb 27;1868(6):140404. doi:, 10.1016/j.bbapap.2020.140404. PMID:32114262<ref>PMID:32114262</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6qjx" style="background-color:#fffaf0;"></div>

==See Also==
*[[Tetracycline repressor protein 3D structures|Tetracycline repressor protein 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Berndt L]]
[[Category: Girbardt B]]
[[Category: Hinrichs W]]
[[Category: Palm GJ]]