Solution structure and dynamics of ribonuclease Sa

Autor: Laurents, D.V., Pérez-Cañadillas, José Manuel, Santoro, Jorge, Rico, Manuel, Schell, David, Pace, C. Nick, Bruix, M.
Přispěvatelé: Dirección General de Investigación Científica y Técnica, DGICT (España), National Institutes of Health (US), Welch Foundation, Leukemia & Lymphoma Society (US)
Rok vydání: 2001
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1097-0134
0887-3585
Popis: We have used NMR methods to characterize the structure and dynamics of ribonuclease Sa in solution. The solution structure of RNase Sa was obtained using the distance constraints provided by 2,276 NOEs and the C6-C96 disulfide bond. The 40 resulting structures are well determined; their mean pairwise RMSD is 0.76 Å (backbone) and 1.26 Å (heavy atoms). The solution structures are similar to previously determined crystal structures, especially in the secondary structure, but exhibit new features: the loop composed of Pro 45 to Ser 48 adopts distinct conformations and the rings of tyrosines 51, 52, and 55 have reduced flipping rates. Amide protons with greatly reduced exchange rates are found predominantly in interior β-strands and the α-helix, but also in the external 3/10 helix and edge β-strand linked by the disulfide bond. Analysis of15N relaxation experiments (R1, R2, and NOE) at 600 MHz revealed five segments, consisting of residues 1-5, 28-31, 46-50, 60-65, 74-77, retaining flexibility in solution. The change in conformation entropy for RNase SA folding is smaller than previously believed, since the native protein is more flexible in solution than in a crystal. © 2001 Wiley-Liss,Inc.
This work supported by the Dirección General de Investigación Científica y Técnica (Spain), grant PB-93-0189 (to M.R.); by the National Institutes of Health, grant GM-37039 (to C.N.P.), and by the Robert A. Welch Foundation, grant A-1060 (to C.N.P.). D.V.L. was a Leukemia and Lymphoma Society of America Fellow.
Databáze: OpenAIRE
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