View source for 2d04


==Crystal structure of neoculin, a sweet protein with taste-modifying activity.==
<StructureSection load='2d04' size='340' side='right'caption='[[2d04]], [[Resolution|resolution]] 2.76&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2d04]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Molineria_latifolia Molineria latifolia]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2D04 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2D04 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]] 2.76&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=FUL:BETA-L-FUCOSE'>FUL</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=2d04 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2d04 OCA], [https://pdbe.org/2d04 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2d04 RCSB], [https://www.ebi.ac.uk/pdbsum/2d04 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2d04 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CURC2_MOLLA CURC2_MOLLA] Taste-modifying protein; sweet-tasting. After curculin, water elicits a sweet taste, and sour substances induce a stronger sense of sweetness.
== 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/d0/2d04_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=2d04 ConSurf].
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== Publication Abstract from PubMed ==
Although the majority of sweet compounds are of low molecular mass, several proteins are known to elicit sweet taste responses in humans. The fruit of Curculigo latifolia contains a heterodimeric protein, neoculin, which has both sweetness and a taste-modifying activity that converts sourness to sweetness. Here, we report the crystal structure of neoculin at 2.76A resolution. This is the first well-defined tertiary structure of a taste-modifying protein of this kind. The overall structure is quite similar to those of monocot mannose-binding lectins. However, crucial topological differences are observed in the C-terminal regions of both subunits. In both subunits of neoculin, the C-terminal tails turn up to form loops fixed by inter-subunit disulfide bonds that are not observed in the lectins. Indeed, the corresponding regions of the lectins stretch straight over the surface of another subunit. Such a C-terminal structural feature as is observed in neoculin results in a decrease in subunit-subunit interactions. Moreover, distribution of electrostatic potential on the surface of neoculin is unique and significantly different from those of the lectins, particularly in the basic subunit (NBS). We have found that there is a large cluster composed of six basic residues on the surface of NBS, and speculate that it might be involved in the elicitation of sweetness and/or taste-modifying activity of neoculin. Molecular dynamics simulation based on the crystallography results suggests that neoculin may adopt a widely "open" conformation at acidic pH, while unprotonated neoculin at neutral pH is in a "closed" conformation. Based on these simulations and the generation of a docking model between neoculin and the sweet-taste receptor, T1R2-T1R3, we propose the hypothesis that neoculin is in dynamic equilibrium between open and closed states, and that the addition of an acid shifts the equilibrium to the open state, allowing ligand-receptor interaction.

Crystal structure of neoculin: insights into its sweetness and taste-modifying activity.,Shimizu-Ibuka A, Morita Y, Terada T, Asakura T, Nakajima K, Iwata S, Misaka T, Sorimachi H, Arai S, Abe K J Mol Biol. 2006 May 26;359(1):148-58. Epub 2006 Mar 29. PMID:16616933<ref>PMID:16616933</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2d04" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Molineria latifolia]]
[[Category: Abe K]]
[[Category: Arai S]]
[[Category: Asakura T]]
[[Category: Iwata S]]
[[Category: Misaka T]]
[[Category: Morita Y]]
[[Category: Nakajima K]]
[[Category: Shimizu-Ibuka A]]
[[Category: Sorimachi H]]
[[Category: Terada T]]