title: Interplay of structure and disorder in cochaperonin mobile loops.
abstract: Protein-protein interactions typically are characterized by highly specific interfaces that mediate binding with precisely tuned affinities. Binding of the Escherichia coli cochaperonin GroES to chaperonin GroEL is mediated, at least in part, by a mobile polypeptide loop in GroES that becomes immobilized in the GroEL/GroES/nucleotide complex. The bacteriophage T4 cochaperonin Gp31 possesses a similar highly flexible polypeptide loop in a region of the protein that shows low, but significant, amino acid similarity with GroES and other cochaperonins. When bound to GroEL, a synthetic peptide representing the mobile loop of either GroES or Gp31 adopts a characteristic bulged hairpin conformation as determined by transferred nuclear Overhauser effects in NMR spectra. Thermodynamic considerations suggest that flexible disorder in the cochaperonin mobile loops moderates their affinity for GroEL to facilitate cycles of chaperonin-mediated protein folding.
authors.affiliation: Department of Biochemistry, Tulane University School of Medicine, New Orleans, LA 70112-2699, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Landry
authors.forename: A
authors.initials: A
authors.lastname: Taher
authors.forename: C
authors.initials: C
authors.lastname: Georgopoulos
authors.forename: S M
authors.initials: SM
authors.lastname: van der Vies
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002151:Calorimetry; D018835:Chaperonin 10 / Q000737:chemistry* / Q000378:metabolism*; D018834:Chaperonin 60 / Q000737:chemistry* / Q000378:metabolism*; D019277:Entropy; D004926:Escherichia coli / Q000378:metabolism*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010449:Peptide Mapping; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D018835:Chaperonin 10; D018834:Chaperonin 60; D010446:Peptide Fragments