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Titolo:
A kinetic analysis of the nucleotide-induced allosteric transitions of GroEL
Autore:
Cliff, MJ; Kad, NM; Hay, N; Lund, PA; Webb, MR; Burston, SG; Clarke, AR;
Indirizzi:
Univ Bristol, Sch Med Sci, Dept Biochem, Bristol BS8 1TD, Avon, England Univ Bristol Bristol Avon England BS8 1TD Bristol BS8 1TD, Avon, England Univ Birmingham, Dept Biochem, Birmingham B15 2TT, W Midlands, England Univ Birmingham Birmingham W Midlands England B15 2TT W Midlands, England Natl Inst Med Res, London NW7 1AA, England Natl Inst Med Res London England NW7 1AA ed Res, London NW7 1AA, England
Titolo Testata:
JOURNAL OF MOLECULAR BIOLOGY
fascicolo: 3, volume: 293, anno: 1999,
pagine: 667 - 684
SICI:
0022-2836(19991029)293:3<667:AKAOTN>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
INDUCED CONFORMATIONAL-CHANGES; OLIGOMERIC CHAPERONIN GROEL; ESCHERICHIA-COLI; ATPASE CYCLE; CRYSTAL-STRUCTURE; POLYPEPTIDE BINDING; FOLDING REACTION; PROTEIN; RELEASE; MECHANISM;
Keywords:
chaperonins; GroEL; ATP; transient kinetic analysis; allostery;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
54
Recensione:
Indirizzi per estratti:
Indirizzo: Cliff, MJ Univ Bristol, Sch Med Sci, Dept Biochem, Univ Walk, Bristol BS8 1TD, Avon,England Univ Bristol Univ Walk Bristol Avon England BS8 1TD Avon,England
Citazione:
M.J. Cliff et al., "A kinetic analysis of the nucleotide-induced allosteric transitions of GroEL", J MOL BIOL, 293(3), 1999, pp. 667-684

Abstract

Single-point mutants of GroEL were constructed with tryptophan replacing atyrosine residue in order to examine nucleotide-induced structural transitions spectrofluorometrically. The tyrosine residues at positions 203, 360, 476 and 485 were mutated. Of these, the probe at residue 485 gave the dearest fluorescence signals upon nucleotide binding. The probe at 360 reported similar signals. In response to the binding of ATP, the indole fluorescencereports four distinct structural transitions occurring on well-separated timescales, all of which precede hydrolysis of the nucleotide. All four of these rearrangements were analysed, two in detail. The fastest is an order of magnitude more rapid than previously identified rearrangements and is proposed to be a T-to-R transition. The next kinetic phase is a rearrangement to the open state identified by electron cryo-microscopy and this we designate an R to R* transition. Both of these rearrangements can occur when onlya single ring of GroEL is loaded with ATP, and the results are consistent with the occupied ring behaving in a concerted, cooperative manner. At higher ATP concentrations both rings can be loaded with the nucleotide and the R to R* transition is accelerated. The resultant GroEL:ATP(14) species can then undergo two final rearrangements, RR* --> [RR](+) --> [RR](#). These final slow steps are completely blocked when ADP occupies the second ring, i.e. it does not occur in the GroEL:ATP(7):ADP(7) or the GroEL:ATP(7) species. All equilibrium and kinetic data conform to a minimal model in which theGroEL ring can exist in five distinct states which then give rise to seventypes of oligomeric conformer: TT, TR, TR*, RR, RR*, [RR](+) and [RR](#), with concerted transitions between each. The other eight possible conformers are presumably disallowed by constraints imposed by interring contacts. This kinetic behaviour is consistent with the GroEL ring passing through distinct functional states in a binding-encapsulation-folding process, with the T-form having high substrate affinity (binding), the R-form being able tobind GroES but retaining substrate affinity (encapsulation), and the R*-form retaining high GroES affinity but allowing the substrate to dissociate into the enclosed cavity (folding). ADP induces only one detectable rearrangement (designated T to T*) which has no properties in common with those elicited by ATP. However, asymmetric ADP binding prevents ATP occupying both rings and, hence, restricts the system to the T*T, T*R and T*R* complexes. (C) 1999 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/07/20 alle ore 14:56:50