title: WW: An isolated three-stranded antiparallel beta-sheet domain that unfolds and refolds reversibly; evidence for a structured hydrophobic cluster in urea and GdnHCl and a disordered thermal unfolded state.
abstract: The objective of this study was to evaluate the suitability of the WW domain as a desirable model system to understand the folding and stability of an isolated three-stranded antiparallel beta-sheet structure. The WW domain was subjected to thermal and chaotropic denaturation/reconstitution utilizing a variety of biophysical methods. This three-stranded sheet folds reversibly and cooperatively utilizing both urea and GdnHCl as denaturants; however, the denatured state retains structure in the form of a hydrophobic cluster involving at least one aromatic side chain. In contrast to chaotropic denaturation, thermal denaturation appears to be more complete and may be a two state process. The suitability of the WW domain for future studies aimed at understanding the kinetics and thermodynamics of antiparallel beta-sheet folding clearly emerges from this initial study. The most exciting and significant result in this manuscript is the finding that the chaotropic denatured state of WW has a hydrophobic cluster as discerned by near-UV CD evidence. The role that the denatured state plays in the folding and stability of a three-stranded beta-sheets, and its capacity for preventing aggregation may be particularly important and is the subject of ongoing studies.
authors.affiliation: Department of Chemistry and the Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: E K
authors.initials: EK
authors.lastname: Koepf
authors.forename: H M
authors.initials: HM
authors.lastname: Petrassi
authors.forename: M
authors.initials: M
authors.lastname: Sudol
authors.forename: J W
authors.initials: JW
authors.lastname: Kelly
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001669:Biochemical Phenomena; D002352:Carrier Proteins / Q000737:chemistry; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D019791:Guanidine / Q000737:chemistry*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015233:Models, Statistical; D010750:Phosphoproteins / Q000737:chemistry; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics; D014157:Transcription Factors; D014508:Urea / Q000737:chemistry; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D010750:Phosphoproteins; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C088374:YAP1 protein, human; D014508:Urea; D019791:Guanidine