Streptavidin and its biotin complex at atomic resolution
- University of Washington, Box 35742, Seattle, WA 98195-7420 (United States)
- University of Washington, Box 355061, Seattle, WA 98195-5061 (United States)
- Vanderbilt University, 5142 Medical Research Building III, 465 21st Avenue South, Nashville, TN 37232-8725 (United States)
Analysis of atomic resolution crystal structures of wild-type streptavidin (1.03 Å) and its biotin complex (0.95 Å) indicate the range of conformational states taken on by this protein in the solid state. Most of the structural variation is found in the polypeptide loops between the strands in this β-sandwich protein. Atomic resolution crystallographic studies of streptavidin and its biotin complex have been carried out at 1.03 and 0.95 Å, respectively. The wild-type protein crystallized with a tetramer in the asymmetric unit, while the crystals of the biotin complex contained two subunits in the asymmetric unit. Comparison of the six subunits shows the various ways in which the protein accommodates ligand binding and different crystal-packing environments. Conformational variation is found in each of the polypeptide loops connecting the eight strands in the β-sandwich subunit, but the largest differences are found in the flexible binding loop (residues 45–52). In three of the unliganded subunits the loop is in an ‘open’ conformation, while in the two subunits binding biotin, as well as in one of the unliganded subunits, this loop ‘closes’ over the biotin–binding site. The ‘closed’ loop contributes to the protein’s high affinity for biotin. Analysis of the anisotropic displacement parameters included in the crystallographic models is consistent with the variation found in the loop structures and the view that the dynamic nature of the protein structure contributes to the ability of the protein to bind biotin so tightly.
- OSTI ID:
- 22351242
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 67, Issue Pt 9; Other Information: PMCID: PMC3169315; PMID: 21904034; PUBLISHER-ID: wd5158; OAI: oai:pubmedcentral.nih.gov:3169315; Copyright (c) International Union of Crystallography 2011; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
Similar Records
The structure of the SBP-Tag–streptavidin complex reveals a novel helical scaffold bridging binding pockets on separate subunits
Molecular origins of the slow streptavidin-biotin dissociation kinetics