title: Destabilization of the complete protein secondary structure on binding to the chaperone GroEL.
abstract: Protein folding in vivo is mediated by helper proteins, the molecular chaperones, of which Hsp60 and its Escherichia coli variant GroEL are some of the best characterized. GroEL is an oligomeric protein with 14 subunits each of M(r) 60K, which possesses weak, co-operative ATPase activity and high plasticity. GroEL seems to interact with non-native proteins, binding one or two molecules per 14-mer in a 'central cavity', but little is known about the conformational state of the bound polypeptides. Here we use nuclear magnetic resonance techniques to show that the interaction of the small protein cyclophilin with GroEL is reversible by temperature changes, and all amide protons in GroEL-bound cyclophilin are exchanged with the solvent, although this exchange does not occur in free cyclophilin. The complete secondary structure of cyclophilin must be disrupted when bound to GroEL.
authors.affiliation: Max-Planck-Institut für Biochemie, Protein Engineering Group, Martinsried, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Zahn
authors.forename: C
authors.initials: C
authors.lastname: Spitzfaden
authors.forename: M
authors.initials: M
authors.lastname: Ottiger
authors.forename: K
authors.initials: K
authors.lastname: Wüthrich
authors.forename: A
authors.initials: A
authors.lastname: Plückthun
mesh_terms: D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018834:Chaperonin 60; D003903:Deuterium / Q000737:chemistry; D004926:Escherichia coli; D006360:Heat-Shock Proteins / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D019696:Peptidylprolyl Isomerase; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; D003903:Deuterium; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase