3rdq

<StructureSection load='3rdq' size='340' side='right' caption='[[3rdq]], [[Resolution|resolution]] 1.60&Aring;' scene=''>

<table><tr><td colspan='2'>[[3rdq]] is a 1 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=3RDQ OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3RDQ FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=DTB:6-(5-METHYL-2-OXO-IMIDAZOLIDIN-4-YL)-HEXANOIC+ACID'>DTB</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=NI:NICKEL+(II)+ION'>NI</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3rdm|3rdm]], [[3rdo|3rdo]], [[3rds|3rds]], [[3rdu|3rdu]], [[3rdx|3rdx]], [[3re5|3re5]], [[3re6|3re6]]</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=3rdq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3rdq OCA], [http://pdbe.org/3rdq PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3rdq RCSB], [http://www.ebi.ac.uk/pdbsum/3rdq PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3rdq ProSAT]</span></td></tr>

[[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).

We have performed a detailed analysis of streptavidin variants with altered specificity towards desthiobiotin. In addition to changes in key residues which widen the ligand binding pocket and accommodate the more structurally flexible desthiobiotin, the data revealed the role of a key, non-active site mutation at the base of the flexible loop (S52G) which slows dissociation of this ligand by approximately sevenfold. Our data suggest that this mutation results in the loss of a stabilizing contact which keeps this loop open and accessible in the absence of ligand. When this mutation was introduced into the wild-type protein, destabilization of the opened loop conferred a approximately 10-fold decrease in both the on-rate and off-rate for the ligand biotin-4-fluoroscein. A similar effect was observed when this mutation was added to a monomeric form of this protein. Our results provide key insight into the role of the streptavidin flexible loop in ligand binding and maintaining high affinity interactions.

 

== References ==

[[Category: As 4 1583]]

[[Category: Almo, S C]]

[[Category: Czecster, C M]]

[[Category: Guan, R]]

[[Category: Levy, M]]

[[Category: Magalhaes, M]]

[[Category: Malashkevich, V N]]

[[Category: Streptavidin variant]]