3RDO: Crystal structure of R7-2 streptavidin complexed with biotin

Citation:
Abstract
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.
PDB ID: 3RDODownload
MMDB ID: 91386
PDB Deposition Date: 2011/4/1
Updated in MMDB: 2011/07
Experimental Method:
x-ray diffraction
Resolution: 1.404  Å
Source Organism:
Similar Structures:
Biological Unit for 3RDO: monomeric; determined by author
Molecular Components in 3RDO
Label Count Molecule
Protein (1 molecule)
1
Streptavidin
Molecule annotation
Chemicals (5 molecules)
1
1
2
1
3
1
4
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.