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| <StructureSection load='4gd9' size='340' side='right'caption='[[4gd9]], [[Resolution|resolution]] 1.50Å' scene=''> | | <StructureSection load='4gd9' size='340' side='right'caption='[[4gd9]], [[Resolution|resolution]] 1.50Å' scene=''> |
| == Structural highlights == | | == Structural highlights == |
| <table><tr><td colspan='2'>[[4gd9]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/As_4.1583 As 4.1583]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4GD9 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4GD9 FirstGlance]. <br> | | <table><tr><td colspan='2'>[[4gd9]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Streptomyces_avidinii Streptomyces avidinii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4GD9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4GD9 FirstGlance]. <br> |
| </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BTN:BIOTIN'>BTN</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.5Å</td></tr> |
| <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1swf|1swf]]</td></tr> | | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BTN:BIOTIN'>BTN</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'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4gd9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4gd9 OCA], [http://pdbe.org/4gd9 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4gd9 RCSB], [http://www.ebi.ac.uk/pdbsum/4gd9 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4gd9 ProSAT]</span></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=4gd9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4gd9 OCA], [https://pdbe.org/4gd9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4gd9 RCSB], [https://www.ebi.ac.uk/pdbsum/4gd9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4gd9 ProSAT]</span></td></tr> |
| </table> | | </table> |
| == Function == | | == Function == |
| [[http://www.uniprot.org/uniprot/SAV_STRAV SAV_STRAV]] The biological function of streptavidin is not known. Forms a strong non-covalent specific complex with biotin (one molecule of biotin per subunit of streptavidin). | | [https://www.uniprot.org/uniprot/SAV_STRAV SAV_STRAV] The biological function of streptavidin is not known. Forms a strong non-covalent specific complex with biotin (one molecule of biotin per subunit of streptavidin). |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| Circular permutation of streptavidin was carried out in order to investigate the role of a main-chain amide in stabilizing the high-affinity complex of the protein and biotin. Mutant proteins CP49/48 and CP50/49 were constructed to place new N-termini at residues 49 and 50 in a flexible loop involved in stabilizing the biotin complex. Crystal structures of the two mutants show that half of each loop closes over the binding site, as observed in wild-type streptavidin, while the other half adopts the open conformation found in the unliganded state. The structures are consistent with kinetic and thermodynamic data and indicate that the loop plays a role in enthalpic stabilization of the bound state via the Asn49 amide-biotin hydrogen bond. In wild-type streptavidin, the entropic penalties of immobilizing a flexible portion of the protein to enhance binding are kept to a manageable level by using a contiguous loop of medium length (six residues) which is already constrained by its anchorage to strands of the beta-barrel protein. A molecular-dynamics simulation for CP50/49 shows that cleavage of the binding loop results in increased structural fluctuations for Ser45 and that these fluctuations destabilize the streptavidin-biotin complex.
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| Structural consequences of cutting a binding loop: two circularly permuted variants of streptavidin.,Le Trong I, Chu V, Xing Y, Lybrand TP, Stayton PS, Stenkamp RE Acta Crystallogr D Biol Crystallogr. 2013 Jun;69(Pt 6):968-77. doi:, 10.1107/S0907444913003855. Epub 2013 May 11. PMID:23695241<ref>PMID:23695241</ref>
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| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| <div class="pdbe-citations 4gd9" style="background-color:#fffaf0;"></div>
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| ==See Also== | | ==See Also== |
| *[[Avidin 3D structures|Avidin 3D structures]] | | *[[Avidin 3D structures|Avidin 3D structures]] |
| == References ==
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| <references/>
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| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |
| [[Category: As 4 1583]]
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| [[Category: Large Structures]] | | [[Category: Large Structures]] |
| [[Category: Chu, V]] | | [[Category: Streptomyces avidinii]] |
| [[Category: Lybrand, T P]] | | [[Category: Chu V]] |
| [[Category: Stayton, P S]]
| | [[Category: Le Trong I]] |
| [[Category: Stenkamp, R E]]
| | [[Category: Lybrand TP]] |
| [[Category: Trong, I Le]] | | [[Category: Stayton PS]] |
| [[Category: Xing, Y]] | | [[Category: Stenkamp RE]] |
| [[Category: Biotin]] | | [[Category: Xing Y]] |
| [[Category: Biotin-binding protein]] | |
| [[Category: Circular permutation]] | |