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[[Image:2e7t.jpg|left|200px]]<br /><applet load="2e7t" size="350" color="white" frame="true" align="right" spinBox="true"
caption="2e7t, resolution 2.65&Aring;" />
'''Crystal structure of basic winged bean lectin in complex with a blood group trisaccharide'''<br />


==Overview==
==Crystal structure of basic winged bean lectin in complex with a blood group trisaccharide==
Basic winged bean agglutinin binds A-blood group substance with higher, affinity and B-blood group substance with lesser affinity. It does not, bind the O substance. The crystal structures of the lectin, complexed with, A-reactive and B-reactive di and tri saccharides, have been determined. In, addition, the complexes of the lectin with fucosylated A-trisaccharides, and B-trisaccharides and with a variant of the A-trisaccharide have been, modeled. These structures and models provide valuable insights into the, structural basis of blood group specificities. All the four carbohydrate, binding loops of the lectin contribute to the primary combining site while, the loop of variable length contributes to the secondary binding site. In, a significant advance to the current understanding, the interactions at, the secondary binding site also contribute substantially, albeit in a, subtle manner, to determine the blood group specificity. Compared with the, interactions of the B-trisaccharide with the lectin, the third sugar, residue of the A-reactive trisacharide forms an additional hydrogen bond, with a lysine residue in the variable loop. In the former, the formation, of such a hydrogen bond is prevented by a shift in the orientation of, third sugar resulting from an internal hydrogen bond in it. The formation, of this bond is also facilitated by an interaction dependent change in the, rotamer conformation of the lysyl residue of the variable loop. Thus, the, difference in the interactions at the secondary site is generated by, coordinated movements in the ligand as well as the protein. A comparison, of the crystal structure and the model of the complex involving the, variant of the A-trisaccharide results in the delineation of the relative, contributions of the interactions at the primary and the secondary sites, in determining blood group specificity. Proteins 2007. (c) 2007, Wiley-Liss, Inc.
<StructureSection load='2e7t' size='340' side='right'caption='[[2e7t]], [[Resolution|resolution]] 2.65&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2e7t]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Psophocarpus_tetragonolobus Psophocarpus tetragonolobus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2E7T OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2E7T 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]] 2.65&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=A2G:N-ACETYL-2-DEOXY-2-AMINO-GALACTOSE'>A2G</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=FUC:ALPHA-L-FUCOSE'>FUC</scene>, <scene name='pdbligand=GAL:BETA-D-GALACTOSE'>GAL</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</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=2e7t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2e7t OCA], [https://pdbe.org/2e7t PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2e7t RCSB], [https://www.ebi.ac.uk/pdbsum/2e7t PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2e7t ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/LEC1_PSOTE LEC1_PSOTE] Lectin.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/e7/2e7t_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2e7t ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Basic winged bean agglutinin binds A-blood group substance with higher affinity and B-blood group substance with lesser affinity. It does not bind the O substance. The crystal structures of the lectin, complexed with A-reactive and B-reactive di and tri saccharides, have been determined. In addition, the complexes of the lectin with fucosylated A-trisaccharides and B-trisaccharides and with a variant of the A-trisaccharide have been modeled. These structures and models provide valuable insights into the structural basis of blood group specificities. All the four carbohydrate binding loops of the lectin contribute to the primary combining site while the loop of variable length contributes to the secondary binding site. In a significant advance to the current understanding, the interactions at the secondary binding site also contribute substantially, albeit in a subtle manner, to determine the blood group specificity. Compared with the interactions of the B-trisaccharide with the lectin, the third sugar residue of the A-reactive trisacharide forms an additional hydrogen bond with a lysine residue in the variable loop. In the former, the formation of such a hydrogen bond is prevented by a shift in the orientation of third sugar resulting from an internal hydrogen bond in it. The formation of this bond is also facilitated by an interaction dependent change in the rotamer conformation of the lysyl residue of the variable loop. Thus, the difference in the interactions at the secondary site is generated by coordinated movements in the ligand as well as the protein. A comparison of the crystal structure and the model of the complex involving the variant of the A-trisaccharide results in the delineation of the relative contributions of the interactions at the primary and the secondary sites in determining blood group specificity.


==About this Structure==
Generation of blood group specificity: new insights from structural studies on the complexes of A- and B-reactive saccharides with basic winged bean agglutinin.,Kulkarni KA, Katiyar S, Surolia A, Vijayan M, Suguna K Proteins. 2007 Aug 15;68(3):762-9. PMID:17510954<ref>PMID:17510954</ref>
2E7T is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Psophocarpus_tetragonolobus Psophocarpus tetragonolobus] with <scene name='pdbligand=MN:'>MN</scene> and <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2E7T OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
Generation of blood group specificity: New insights from structural studies on the complexes of A- and B-reactive saccharides with basic winged bean agglutinin., Kulkarni KA, Katiyar S, Surolia A, Vijayan M, Suguna K, Proteins. 2007 May 17;. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17510954 17510954]
</div>
<div class="pdbe-citations 2e7t" style="background-color:#fffaf0;"></div>
 
==See Also==
*[[Agglutinin 3D structures|Agglutinin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Psophocarpus tetragonolobus]]
[[Category: Psophocarpus tetragonolobus]]
[[Category: Single protein]]
[[Category: Katiyar S]]
[[Category: Katiyar, S.]]
[[Category: Kulkarni KA]]
[[Category: Kulkarni, K.A.]]
[[Category: Suguna K]]
[[Category: Suguna, K.]]
[[Category: Surolia A]]
[[Category: Surolia, A.]]
[[Category: Vijayan M]]
[[Category: Vijayan, M.]]
[[Category: CA]]
[[Category: MN]]
[[Category: jelly roll]]
[[Category: lectin]]
[[Category: sugar binding protein]]
 
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