Expansion and compression of a protein folding intermediate by GroEL.
The GroEL-GroES chaperonin system is required for the assisted folding of many essential proteins. The precise nature of this assistance remains unclear, however. Here we show that denatured RuBisCO from Rhodospirillum rubrum populates a stable, nonaggregating, and kinetically trapped monomeric state at low temperature. Productive folding of this nonnative intermediate is fully dependent on GroEL, GroES, and ATP. Reactivation of the trapped RuBisCO monomer proceeds through a series of GroEL-induced structural rearrangements, as judged by resonance energy transfer measurements between the amino- and carboxy-terminal domains of RuBisCO. A general mechanism used by GroEL to push large, recalcitrant proteins like RuBisCO toward their native states thus appears to involve two steps: partial unfolding or rearrangement of a nonnative protein upon capture by a GroEL ring, followed by spatial constriction within the GroEL-GroES cavity that favors or enforces compact, folding-competent intermediate states.
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Zong
Z
Lin
Hays S
HS
Rye
D000255:Adenosine Triphosphate / Q000378:metabolism; D018835:Chaperonin 10 / Q000737:chemistry / Q000378:metabolism; D018834:Chaperonin 60 / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012247:Rhodospirillum rubrum / Q000737:chemistry / Q000201:enzymology; D012273:Ribulose-Bisphosphate Carboxylase / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D013997:Time Factors
D018835:Chaperonin 10; D018834:Chaperonin 60; D000255:Adenosine Triphosphate; D012273:Ribulose-Bisphosphate Carboxylase