4GDA
Circular Permuted Streptavidin A50/N49
Summary for 4GDA
| Entry DOI | 10.2210/pdb4gda/pdb |
| Related | 1SWF |
| Descriptor | Streptavidin, BIOTIN, GLYCEROL, ... (6 entities in total) |
| Functional Keywords | biotin-binding protein, biotin, circular permutation |
| Biological source | Streptomyces avidinii More |
| Cellular location | Secreted: P22629 |
| Total number of polymer chains | 2 |
| Total formula weight | 28178.31 |
| Authors | Le Trong, I.,Chu, V.,Xing, Y.,Lybrand, T.P.,Stayton, P.S.,Stenkamp, R.E. (deposition date: 2012-07-31, release date: 2013-06-05, Last modification date: 2024-02-28) |
| Primary citation | Le Trong, I.,Chu, V.,Xing, Y.,Lybrand, T.P.,Stayton, P.S.,Stenkamp, R.E. Structural consequences of cutting a binding loop: two circularly permuted variants of streptavidin. Acta Crystallogr.,Sect.D, 69:968-977, 2013 Cited by PubMed Abstract: 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 β-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. PubMed: 23695241DOI: 10.1107/S0907444913003855 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1 Å) |
Structure validation
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