title: Symmetric complexes of GroE chaperonins as part of the functional cycle.
abstract: The particular structural arrangement of chaperonins probably contributes to their ability to assist in the folding of proteins. The interaction of the oligomeric bacterial chaperonin GroEL and its cochaperonin, GroES, in the presence of adenosine diphosphate (ADP) forms an asymmetric complex. However, in the presence of adenosine triphosphate (ATP) or its nonhydrolyzable analogs, symmetric complexes were found by electron microscopy and image analysis. The existence of symmetric chaperonin complexes is not predicted by current models of the functional cycle for GroE-mediated protein folding. Because complete folding of a nonnative substrate protein in the presence of GroEL and GroES only occurs in the presence of ATP, but not with ADP, the symmetric chaperonin complexes formed during the GroE cycle are proposed to be functionally significant.
authors.affiliation: Institut für Biophysik und Physikalische Biochemie, Universität Regensburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
authors.forename: K
authors.initials: K
authors.lastname: Rutkat
authors.forename: R
authors.initials: R
authors.lastname: Rachel
authors.forename: G
authors.initials: G
authors.lastname: Pfeifer
authors.forename: R
authors.initials: R
authors.lastname: Jaenicke
authors.forename: P
authors.initials: P
authors.lastname: Viitanen
authors.forename: G
authors.initials: G
authors.lastname: Lorimer
authors.forename: J
authors.initials: J
authors.lastname: Buchner
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D001704:Biopolymers; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D006868:Hydrolysis; D008854:Microscopy, Electron; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D001704:Biopolymers; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases