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Concerted ATP-induced allosteric transitions in GroEL facilitate release of protein substrate domains in an all-or-none manner

Kipnis, Yakov, Papo, Niv, Haran, Gilad, Horovitz, Amnon
Proceedings of the National Academy of Sciences of the United States of America 2007 v.104 no.9 pp. 3119-3124
chimerism, denaturation, protein folding
The double-ring chaperonin GroEL mediates protein folding, in conjunction with its helper protein GroES, by undergoing ATP-induced conformational changes that are concerted within each heptameric ring. Here we have examined whether the concerted nature of these transitions is responsible for protein substrate release in an all-or-none manner. Two chimeric substrates were designed, each with two different reporter activities that were recovered after denaturation in GroES-dependent and independent fashions, respectively. The refolding of the chimeras was monitored in the presence of GroEL variants that undergo ATP-induced intraring conformational changes that are either sequential (F44W/D155A) or concerted (F44W). Our results show that release of a protein substrate from GroEL in a domain-by-domain fashion is favored when the intraring allosteric transitions of GroEL are sequential and not concerted.