View source for 4b3a


==Tetracycline repressor class D mutant H100A in complex with tetracycline==
<StructureSection load='4b3a' size='340' side='right'caption='[[4b3a]], [[Resolution|resolution]] 1.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4b3a]] 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=4B3A OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4B3A 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='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=TAC:TETRACYCLINE'>TAC</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=4b3a FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4b3a OCA], [https://pdbe.org/4b3a PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4b3a RCSB], [https://www.ebi.ac.uk/pdbsum/4b3a PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4b3a 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 4b3a" 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: Eltschkner S]]
[[Category: Hinrichs W]]
[[Category: Palm GJ]]
[[Category: Schindler S]]
[[Category: Schneider J]]