3rdx

Crystal structure of ligand-free R7-2 streptavidin

spinqualitylabelsall models 3rdx, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3rdx is a 2 chain structure with sequence from As 4.1583. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL Related: 3rdm, 3rdo, 3rdq, 3rds, 3rdu, 3re5, 3re6 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [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). Publication Abstract from PubMed 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. Evolved streptavidin mutants reveal key role of loop residue in high-affinity binding.,Magalhaes ML, Czekster CM, Guan R, Malashkevich VN, Almo SC, Levy M Protein Sci. 2011 Jul;20(7):1145-54. doi: 10.1002/pro.642. Epub 2011 May, 12. PMID:21520321 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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