title: GroEL stimulates protein folding through forced unfolding.
abstract: Many proteins cannot fold without the assistance of chaperonin machines like GroEL and GroES. The nature of this assistance, however, remains poorly understood. Here we demonstrate that unfolding of a substrate protein by GroEL enhances protein folding. We first show that capture of a protein on the open ring of a GroEL-ADP-GroES complex, GroEL's physiological acceptor state for non-native proteins in vivo, leaves the substrate protein in an unexpectedly compact state. Subsequent binding of ATP to the same GroEL ring causes rapid, forced unfolding of the substrate protein. Notably, the fraction of the substrate protein that commits to the native state following GroES binding and protein release into the GroEL-GroES cavity is proportional to the extent of substrate-protein unfolding. Forced protein unfolding is thus a central component of the multilayered stimulatory mechanism used by GroEL to drive protein folding.
authors.affiliation: Department of Molecular Biology, Princeton University, Schultz Laboratory, Princeton, New Jersey 08544, USA.
authors.forename: Zong
authors.initials: Z
authors.lastname: Lin
authors.forename: Damian
authors.initials: D
authors.lastname: Madan
authors.forename: Hays S
authors.initials: HS
authors.lastname: Rye
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001059:Apoproteins / Q000378:metabolism; D018834:Chaperonin 60 / Q000737:chemistry* / Q000378:metabolism*; D003545:Cysteine; D008954:Models, Biological; D010447:Peptide Hydrolases / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry
chemical_list: D001059:Apoproteins; D018834:Chaperonin 60; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010447:Peptide Hydrolases; D012273:Ribulose-Bisphosphate Carboxylase; D003545:Cysteine