title: Domain swapping proceeds via complete unfolding: a 19F- and 1H-NMR study of the Cyanovirin-N protein.
abstract: Domain swapping creates protein oligomers by exchange of structural units between identical monomers. At present, no unifying molecular mechanism of domain swapping has emerged. Here we used the protein Cyanovirin-N (CV-N) and (19)F-NMR to investigate the process of domain swapping. CV-N is an HIV inactivating protein that can exist as a monomer or a domain-swapped dimer. We measured thermodynamic and kinetic parameters of the conversion process and determined the size of the energy barrier between the two species. The barrier is very large and of similar magnitude to that for equilibrium unfolding of the protein. Therefore, for CV-N, overall unfolding of the polypeptide is required for domain swapping.
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: In-Ja L
authors.initials: IJ
authors.lastname: Byeon
authors.forename: Ivet
authors.initials: I
authors.lastname: Bahar
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002352:Carrier Proteins / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D058767:Protein Unfolding; D011522:Protons; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D011522:Protons; C107733:cyanovirin N; D005461:Fluorine