Characterization of the structure and function of W -> FWW domain variants: Identification of a natively unfolded protein that folds upon ligand binding

Citation
Ek. Koepf et al., Characterization of the structure and function of W -> FWW domain variants: Identification of a natively unfolded protein that folds upon ligand binding, BIOCHEM, 38(43), 1999, pp. 14338-14351
Citations number
43
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMISTRY
ISSN journal
00062960 → ACNP
Volume
38
Issue
43
Year of publication
1999
Pages
14338 - 14351
Database
ISI
SICI code
0006-2960(19991026)38:43<14338:COTSAF>2.0.ZU;2-4
Abstract
The WW domain adopts a compact, three-stranded, antiparallel P-sheet struct ure that mediates protein-protein interactions by binding to xPPxY-based pr otein ligands? such as the PY-ligand (EYPPYPPPPYPSG) derived from p53 bindi ng protein-2. The conserved Trp residues, after which this domain was named , were replaced with Phe so their importance in structural integrity and fo r ligand binding could be evaluated. A biophysical approach was employed to compare the W17F, W39F, and W17F/W39F WW domains to the wild-type protein. The data demonstrate that replacement of Trp39 with Phe (W39F) does not di srupt the structure of the WW domain variant, but does abolish ligand bindi ng. In contrast. the W17F WW domain variant is largely if not completely un folded; however this variant undergoes a PY-ligand induced disorder to orde r (folding) transition. The dissociation constant for the W17F WW domain-PY -ligand interaction is 15.1 +/- 1.2 mu M, only slightly higher than that ob served for the wild-type WW domain interaction (5.9 +/- 0.33 mu M). The W17 F WW domain is a natively unfolded protein which adopts a native conformati on upon PY-ligand binding.