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==Crystal structure of the sensory domain of the Campylobacter jejuni chemoreceptor Tlp3 (CcmL) with isoleucine bound.==
<StructureSection load='4xmr' size='340' side='right'caption='[[4xmr]], [[Resolution|resolution]] 1.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4xmr]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Campylobacter_jejuni_subsp._jejuni_NCTC_11168_=_ATCC_700819 Campylobacter jejuni subsp. jejuni NCTC 11168 = ATCC 700819]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4XMR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4XMR 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]] 1.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ILE:ISOLEUCINE'>ILE</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=4xmr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4xmr OCA], [https://pdbe.org/4xmr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4xmr RCSB], [https://www.ebi.ac.uk/pdbsum/4xmr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4xmr ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q0P864_CAMJE Q0P864_CAMJE] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Chemotaxis, mediated by methyl-accepting chemotaxis protein (MCP) receptors, plays an important role in the ecology of bacterial populations. This paper presents the first crystallographic analysis of the structure and ligand-induced conformational changes of the periplasmic tandem Per-Arnt-Sim (PAS) sensing domain (PTPSD) of a characterized MCP chemoreceptor. Analysis of the complex of the Campylobacter jejuni Tlp3 PTPSD with isoleucine (a chemoattractant) revealed that the PTPSD is a dimer in the crystal. The two ligand-binding sites are located in the membrane-distal PAS domains on the faces opposite to the dimer interface. Mutagenesis experiments show that the five strongly conserved residues that stabilize the main-chain moiety of isoleucine are essential for binding, suggesting that the mechanism by which this family of chemoreceptors recognizes amino acids is highly conserved. Although the fold and mode of ligand binding of the PTPSD are different from the aspartic acid receptor Tar, the structural analysis suggests that the PTPSDs of amino-acid chemoreceptors are also likely to signal by a piston displacement mechanism. The PTPSD fluctuates between piston (C-terminal helix) `up' and piston `down' states. Binding of an attractant to the distal PAS domain locks it in the closed form, weakening its association with the proximal domain and resulting in the transition of the latter into an open form, concomitant with a downward (towards the membrane) 4 A piston displacement of the C-terminal helix. In vivo, this movement would generate a transmembrane signal by driving a downward displacement of the transmembrane helix 2 towards the cytoplasm.

Structural basis for amino-acid recognition and transmembrane signalling by tandem Per-Arnt-Sim (tandem PAS) chemoreceptor sensory domains.,Liu YC, Machuca MA, Beckham SA, Gunzburg MJ, Roujeinikova A Acta Crystallogr D Biol Crystallogr. 2015 Oct;71(Pt 10):2127-36. doi:, 10.1107/S139900471501384X. Epub 2015 Sep 30. PMID:26457436<ref>PMID:26457436</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4xmr" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Campylobacter jejuni subsp. jejuni NCTC 11168 = ATCC 700819]]
[[Category: Large Structures]]
[[Category: Liu YC]]
[[Category: Machuca MA]]
[[Category: Roujeinikova A]]