1XX8
NMR Structure of the W24A Mutant of the Hyperthermophile Sac7d Protein
Summary for 1XX8
| Entry DOI | 10.2210/pdb1xx8/pdb |
| Related | 1sap |
| Descriptor | Sac7d (1 entity in total) |
| Functional Keywords | hyperthermophile, dna-binding protein, dna binding protein |
| Biological source | Sulfolobus acidocaldarius |
| Total number of polymer chains | 1 |
| Total formula weight | 7511.78 |
| Authors | Bedell, J.L.,Edmondson, S.P.,Shriver, J.W. (deposition date: 2004-11-04, release date: 2005-02-08, Last modification date: 2024-05-22) |
| Primary citation | Bedell, J.L.,Edmondson, S.P.,Shriver, J.W. Role of a surface tryptophan in defining the structure, stability, and DNA binding of the hyperthermophile protein sac7d Biochemistry, 44:915-925, 2005 Cited by PubMed Abstract: Sac7d is a small, chromatin protein from Sulfolobus acidocaldarius which induces a sharp kink in DNA with intercalation of valine and methionine side chains. The crystal structure of the protein-DNA complex indicates that a surface tryptophan (W24) plays a key role in DNA binding by hydrogen bonding to the DNA at the kink site. We show here that substitution of the solvent-exposed tryptophan with alanine (W24A) led to a significant loss in not only DNA binding affinity but also protein stability. The W24A substitution proved to be one of the most destabilizing surface substitutions in Sac7d. A global linkage analysis of the pH and salt dependence of stability indicated that the protein stability surface (DeltaG vs temperature, pH, and salt concentration) was lowered overall by 2 kcal/mol (from 0 to 100 degrees C, pH 0 to 7, and 0 to 0.3 M KCl). The lower free energy of unfolding could not be attributed to significant structural perturbations of surface electrostatic interactions. Residual dipolar coupling of partially aligned protein and the NMR solution structure of W24A confirmed that the surface substitution resulted in no significant change in structure. Stabilization of this hyperthermophile protein and its DNA complex by a surface cluster of hydrophobic residues involving W24 and the two intercalating side chains is discussed. PubMed: 15654747DOI: 10.1021/bi047823b PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
Download full validation report
