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4qnc

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==Crystal structure of a SemiSWEET in an occluded state==
==Crystal structure of a SemiSWEET in an occluded state==
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<StructureSection load='4qnc' size='340' side='right' caption='[[4qnc]], [[Resolution|resolution]] 2.39&Aring;' scene=''>
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<StructureSection load='4qnc' size='340' side='right'caption='[[4qnc]], [[Resolution|resolution]] 2.39&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
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<table><tr><td colspan='2'>[[4qnc]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4QNC OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4QNC FirstGlance]. <br>
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<table><tr><td colspan='2'>[[4qnc]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Leptospira_biflexa_serovar_Patoc_strain_'Patoc_1_(Paris)' Leptospira biflexa serovar Patoc strain 'Patoc 1 (Paris)']. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4QNC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4QNC FirstGlance]. <br>
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</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=MYS:PENTADECANE'>MYS</scene>, <scene name='pdbligand=OLC:(2R)-2,3-DIHYDROXYPROPYL+(9Z)-OCTADEC-9-ENOATE'>OLC</scene></td></tr>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.388&#8491;</td></tr>
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<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4qnd|4qnd]]</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MYS:PENTADECANE'>MYS</scene>, <scene name='pdbligand=OLC:(2R)-2,3-DIHYDROXYPROPYL+(9Z)-OCTADEC-9-ENOATE'>OLC</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4qnc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4qnc OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4qnc RCSB], [http://www.ebi.ac.uk/pdbsum/4qnc PDBsum]</span></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4qnc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4qnc OCA], [https://pdbe.org/4qnc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4qnc RCSB], [https://www.ebi.ac.uk/pdbsum/4qnc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4qnc ProSAT]</span></td></tr>
</table>
</table>
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<div style="background-color:#fffaf0;">
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== Function ==
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== Publication Abstract from PubMed ==
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[https://www.uniprot.org/uniprot/SWEET_LEPBP SWEET_LEPBP] The homodimer mediates transmembrane sugar transport down a concentration gradient. Transport is probably effected by rocking-type movements, where a cargo-binding cavity opens first on one and then on the other side of the membrane.<ref>PMID:25186729</ref>
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SWEETs and their prokaryotic homologues are monosaccharide and disaccharide transporters that are present from Archaea to plants and humans. SWEETs play crucial roles in cellular sugar efflux processes: that is, in phloem loading, pollen nutrition and nectar secretion. Their bacterial homologues, which are called SemiSWEETs, are among the smallest known transporters. Here we show that SemiSWEET molecules, which consist of a triple-helix bundle, form symmetrical, parallel dimers, thereby generating the translocation pathway. Two SemiSWEET isoforms were crystallized, one in an apparently open state and one in an occluded state, indicating that SemiSWEETs and SWEETs are transporters that undergo rocking-type movements during the transport cycle. The topology of the triple-helix bundle is similar yet distinct to that of the basic building block of animal and plant major facilitator superfamily (MFS) transporters (for example, GLUTs and SUTs). This finding indicates two possibilities: that SWEETs and MFS transporters evolved from an ancestral triple-helix bundle or that the triple-helix bundle represents convergent evolution. In SemiSWEETs and SWEETs, two triple-helix bundles are arranged in a parallel configuration to produce the 6- and 6 + 1-transmembrane-helix pores, respectively. In the 12-transmembrane-helix MFS transporters, four triple-helix bundles are arranged into an alternating antiparallel configuration, resulting in a much larger 2 x 2 triple-helix bundle forming the pore. Given the similarity of SemiSWEETs and SWEETs to PQ-loop amino acid transporters and to mitochondrial pyruvate carriers (MPCs), the structures characterized here may also be relevant to other transporters in the MtN3 clan. The insight gained from the structures of these transporters and from the analysis of mutations of conserved residues will improve the understanding of the transport mechanism, as well as allow comparative studies of the different superfamilies involved in sugar transport and the evolution of transporters in general.
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Structures of bacterial homologues of SWEET transporters in two distinct conformations.,Xu Y, Tao Y, Cheung LS, Fan C, Chen LQ, Xu S, Perry K, Frommer WB, Feng L Nature. 2014 Sep 3. doi: 10.1038/nature13670. PMID:25186729<ref>PMID:25186729</ref>
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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</div>
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== References ==
== References ==
<references/>
<references/>
__TOC__
__TOC__
</StructureSection>
</StructureSection>
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[[Category: F., Liang]]
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[[Category: Large Structures]]
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[[Category: Perry, K]]
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[[Category: Liang F]]
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[[Category: T., Yuyong]]
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[[Category: Perry K]]
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[[Category: X., Yan]]
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[[Category: Yan X]]
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[[Category: Membrane protein]]
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[[Category: Yuyong T]]
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[[Category: Transporter]]
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Current revision

Crystal structure of a SemiSWEET in an occluded state

PDB ID 4qnc

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