In the cold-shock protein CspB from Bacillus subtilis three exposed Phe residues (F15, F17, and F27) are essential for its function in binding to single-stranded nucleic acids. Usually, the hydrophobic Phe side chains are buried in folded proteins. We asked here whether the exposition of the essential Phe residues could be a cause for the very low conformational stability of CspB. Urea-induced and heat-induced equilibrium unfolding transitions were measured for three mutants of CspB, where Phe 15, Phe 17, and Phe 27 were individually replaced by alanine. Unexpectedly, all three mutations strongly destabilized CspB. The aromatic side chains of Phe 15, Phe 17, and Phe 27 in the active site are thus important for both binding to nucleic acids and conformational stability. There is no compromise between function and stability in the active site. Model calculations indicate that, although they are partially exposed to solvent, all three Phe residues nevertheless lose accessible surface upon folding, and this should favor the native state. A different result is obtained with the F38A variant. Phe 38 is hyperexposed in native CspB, and its substitution by Ala is in fact stabilizing. Study holds ProTherm entries: 3518, 3519, 3520, 3521, 3522, 3523, 3524, 3525, 3526, 3527, 14241, 14242, 14243, 14244 Extra Details: protein stability; cold shock protein; nucleic acid binding;,hydrophobic effect
ID: nCo4xHGR
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:21 p.m.
Version: 1
Number of data points | 33 |
Proteins | Cold shock protein CspB ; Cold shock protein CspB |
Unique complexes | 5 |
Assays/Quantities/Protocols | Experimental Assay: ddG ; Experimental Assay: Tm ; Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG_H2O ; Derived Quantity: dTm ; Derived Quantity: ddG_H2O |
Libraries | Mutations for sequence MLEGKVKWFNSEKGFGFIEVEGQDDVFVHFSAIQGEGFKTLEEGQAVSFEIVEGNRGPQAANVTKEA |
Colors: | D | E | R | H | K | S | T | N | Q | A | V | I | L | M | F | Y | W | C | G | P |
---|
Structure ID | Release Date | Resolution | Structure Title |
---|---|---|---|
1CSP | 1993-05-12T00:00:00+0000 | 2.45 | CRYSTAL STRUCTURE OF THE BACILLUS SUBTILIS MAJOR COLD SHOCK PROTEIN, CSPB: A UNIVERSAL NUCLEIC-ACID BINDING DOMAIN |
1CSQ | 1993-05-12T00:00:00+0000 | 2.7 | CRYSTAL STRUCTURE OF THE BACILLUS SUBTILIS MAJOR COLD SHOCK PROTEIN, CSPB: A UNIVERSAL NUCLEIC-ACID BINDING DOMAIN |
1NMF | 1996-02-05T00:00:00+0000 | 0 | MAJOR COLD-SHOCK PROTEIN, NMR, 20 STRUCTURES |
1NMG | 1996-02-05T00:00:00+0000 | 0 | MAJOR COLD-SHOCK PROTEIN, NMR, MINIMIZED AVERAGE STRUCTURE |
2ES2 | 2005-10-25T00:00:00+0000 | 1.78 | Crystal Structure Analysis of the Bacillus Subtilis Cold Shock Protein Bs-CspB in Complex with Hexathymidine |
2F52 | 2005-11-25T00:00:00+0000 | 0 | Solution structure of cold shock protein CspB from Bacillus subtilis in complex with heptathymidine |
2I5L | 2006-08-25T00:00:00+0000 | 2.55 | Crystal structure of Bacillus subtilis Cold Shock Protein variant Bs-CspB M1R/E3K/K65I |
2I5M | 2006-08-25T00:00:00+0000 | 2.3 | Crystal structure of Bacillus subtilis cold shock protein CspB variant A46K S48R |
3PF4 | 2010-10-27T00:00:00+0000 | 1.38 | Crystal structure of Bs-CspB in complex with r(GUCUUUA) |
3PF5 | 2010-10-27T00:00:00+0000 | 1.68 | Crystal structure of Bs-CspB in complex with rU6 |