title: Multivalent binding of nonnative substrate proteins by the chaperonin GroEL.
abstract: The chaperonin GroEL binds nonnative substrate protein in the central cavity of an open ring through exposed hydrophobic residues at the inside aspect of the apical domains and then mediates productive folding upon binding ATP and the cochaperonin GroES. Whether nonnative proteins bind to more than one of the seven apical domains of a GroEL ring is unknown. We have addressed this using rings with various combinations of wild-type and binding-defective mutant apical domains, enabled by their production as single polypeptides. A wild-type extent of binary complex formation with two stringent substrate proteins, malate dehydrogenase or Rubisco, required a minimum of three consecutive binding-proficient apical domains. Rhodanese, a less-stringent substrate, required only two wild-type domains and was insensitive to their arrangement. As a physical correlate, multivalent binding of Rubisco was directly observed in an oxidative cross-linking experiment.
authors.affiliation: Howard Hughes Medical Institute and Department of Genetics, Yale School of Medicine, New Haven, Connecticut 06510, USA.
authors.forename: G W
authors.initials: GW
authors.lastname: Farr
authors.forename: K
authors.initials: K
authors.lastname: Furtak
authors.forename: M B
authors.initials: MB
authors.lastname: Rowland
authors.forename: N A
authors.initials: NA
authors.lastname: Ranson
authors.forename: H R
authors.initials: HR
authors.lastname: Saibil
authors.forename: T
authors.initials: T
authors.lastname: Kirchhausen
authors.forename: A L
authors.initials: AL
authors.lastname: Horwich
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D001665:Binding Sites; D002417:Cattle; D018835:Chaperonin 10 / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D018834:Chaperonin 60 / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D020285:Cryoelectron Microscopy; D003553:Cystine / Q000502:physiology; D004926:Escherichia coli / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008291:Malate Dehydrogenase / Q000737:chemistry*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D046911:Macromolecular Substances; D010455:Peptides; D003553:Cystine; D000255:Adenosine Triphosphate; D008291:Malate Dehydrogenase; D013884:Thiosulfate Sulfurtransferase; D012273:Ribulose-Bisphosphate Carboxylase; D005033:Ethylmaleimide