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Sequence determinants of thermodynamic stability in a WW domain—An all‐β‐sheet protein
Author(s) -
Jäger Marcus,
Dendle Maria,
Kelly Jeffery W.
Publication year - 2009
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.172
Subject(s) - ww domain , beta sheet , chemistry , crystallography , protein folding , sequence (biology) , side chain , protein structure , protein domain , alanine , chemical stability , stereochemistry , denaturation (fissile materials) , ligand (biochemistry) , amino acid residue , residue (chemistry) , biophysics , amino acid , peptide sequence , biochemistry , biology , receptor , organic chemistry , nuclear chemistry , gene , polymer
The stabilities of 66 sequence variants of the human Pin1 WW domain have been determined by equilibrium thermal denaturation experiments. All 34 residues composing the hPin1 WW three‐stranded β‐sheet structure could be replaced one at a time with at least one different natural or non‐natural amino acid residue without leading to an unfolded protein. Alanine substitutions at only four positions within the hPin1 WW domain lead to a partially or completely unfolded protein—in the absence of a physiological ligand. The side chains of these four residues form a conserved, partially solvent‐inaccessible, continuous hydrophobic minicore comprising the N‐ and C‐termini. Ala mutations at five other residues, three of which constitute the ligand binding patch on the concave side of the β‐sheet, significantly destabilize the hPin1 WW domain without leading to an unfolded protein. The remaining mutations affect protein stability only slightly, suggesting that only a small subset of side chain interactions within the hPin1 WW domain are mandatory for acquiring and maintaining a stable, cooperatively folded β‐sheet structure.