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==Crystal Structure of putative amino acid binding periplasmic ABC transporter protein from Candidatus Liberibacter asiaticus in complex with Arginine==
<StructureSection load='6aal' size='340' side='right'caption='[[6aal]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6aal]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Candidatus_Liberibacter_asiaticus_str._psy62 Candidatus Liberibacter asiaticus str. psy62]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6AAL OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6AAL 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]] 2.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=ARG:ARGININE'>ARG</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</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=6aal FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6aal OCA], [https://pdbe.org/6aal PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6aal RCSB], [https://www.ebi.ac.uk/pdbsum/6aal PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6aal ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/C6XGT2_LIBAP C6XGT2_LIBAP] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The amino acid-binding receptors, a component of ABC transporters, have evolved to cater to different specificities and functions. Of particular interest are cystine-binding receptors, which have shown broad specificity. In the present study, a putative periplasmic cystine-binding protein from Candidatus Liberibacter asiaticus (CLasTcyA) was characterized. Analysis of the CLasTcyA sequence and crystal structures in the ligand-bound state revealed novel features of CLasTcyA in comparison to related proteins. One of the unique features found in CLasTcyA structure was the positioning of the C-terminal extended loop of one chain very close to the substrate-binding site of the adjacent monomer in the asymmetric unit. The presence of a disulphide bond, unique to Candidatus Liberibacter family, holds the C-terminal extended loop in position. Analysis of the substrate-binding pocket of CLasTcyA suggested a broad specificity and a completely different orientation of the bound substrates in comparison to related protein structures. The open conformation for one of the two chains of the asymmetric unit in the Arg-bound structure revealed a limited open state (18.4 degrees ) for CLasTcyA as compared to open state of other related proteins (~ 60 degrees ). The strong interaction between Asp126 on helix-alpha5 of small domain and Arg82 (bigger domain) restricts the degree of opening in ligand-free open state. The dissociation constant of 1.26 mum by SPR and 3.7 mum by MST exhibited low affinity for the cystine. This is the first structural characterization of an l-cystine ABC transporter from plant pathogen and our results suggest that CLasTcyA may have evolved to cater to its specific needs for its survival in the host.

Crystal structures of a putative periplasmic cystine-binding protein from Candidatus Liberibacter asiaticus: insights into an adapted mechanism of ligand binding.,Kumar P, Kesari P, Kokane S, Ghosh DK, Kumar P, Sharma AK FEBS J. 2019 May 7. doi: 10.1111/febs.14921. PMID:31063259<ref>PMID:31063259</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6aal" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Candidatus Liberibacter asiaticus str. psy62]]
[[Category: Large Structures]]
[[Category: Ghosh DK]]
[[Category: Kesari P]]
[[Category: Kumar P]]
[[Category: Sharma AK]]