title: Stopped-flow fluorescence analysis of the conformational changes in the GroEL apical domain: relationships between movements in the apical domain and the quaternary structure of GroEL.
abstract: GroEL undergoes numerous conformational alterations in the course of facilitating the folding of various proteins, and the specific movements of the GroEL apical domain are of particular importance in the molecular mechanism. In order to monitor in detail the numerous movements of the GroEL apical domain, we have constructed a mutant chaperonin (GroEL R231W) with wild type-like function and a fluorescent probe introduced into the apical domain. By monitoring the tryptophan fluorescence changes of GroEL R231W upon ATP addition in the presence and absence of the co-chaperonin GroES, we detected a total of four distinct kinetic phases that corresponded to conformational changes of the apical domain and GroES binding. By introducing this mutation into a single ring variant of GroEL (GroEL SR-1), we determined the extent of inter-ring cooperation that was involved in apical domain movements. Surprisingly, we found that the apical domain movements of GroEL were affected only slightly by the change in quaternary structure. Our experiments provide a number of novel insights regarding the dynamic movements of this protein.
authors.affiliation: Department of Biotechnology, Faculty of Engineering, Insitute of Regenerative Medicine and Biofunction, Graduate School of Medical Sciences, Tottori University, Tottori, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Tatsunari
authors.initials: T
authors.lastname: Yoshimi
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Hongo
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Mizobata
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kawata
mesh_terms: D018834:Chaperonin 60 / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry; D008958:Models, Molecular; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D018834:Chaperonin 60