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Nucleotide binding-promoted conformational changes release a nonnative polypeptide from the Escherichia coli chaperonin GroEL.

Abstract：

:The Escherichia coli chaperonins GroEL and GroES facilitate the refolding of polypeptide chains in an ATP hydrolysis-dependent reaction. The elementary steps in the binding and release of polypeptide substrates to GroEL were investigated in surface plasmon resonance studies to measure the rates of binding and dissociation of a normative variant of subtilisin. The rate constants determined for GroEL association with and dissociation from this variant yielded a micromolar dissociation constant, in agreement with independent calorimetric estimates. The rate of GroEL dissociation from the nonnative chain was increased significantly in the presence of 5'-adenylylimidodiphosphate (AMP-PNP), ADP, and ATP, yielding maximal values between 0.04 and 0.22 s(-1). The sigmoidal dependence of the dissociation rate on the concentration of AMP-PNP and ADP indicated that polypeptide dissociation is limited by a concerted conformational change that occurs after nucleotide binding. The dependence of the rate of release on ATP exhibited two sigmoidal transitions attributable to nucleotide binding to the distal and proximal toroid of a GroEL-polypeptide chain complex. The addition of GroES resulted in a marked increase in the rate of nonnative polypeptide release from GroEL, indicating that the cochaperonin binds more rapidly than the dissociation of polypeptides. These data demonstrate the importance of nucleotide binding-promoted concerted conformational changes for the release of chains from GroEL, which correlate with the sigmoidal hydrolysis of ATP by the chaperonin. The implications of these findings are discussed in terms of a working hypothesis for a single cycle of chaperonin action.

journal_name

Proc Natl Acad Sci U S A

journal_title

Proceedings of the National Academy of Sciences of the United States of America

authors

Lin Z,Eisenstein E

doi

10.1073/pnas.93.5.1977

subject

Has Abstract

pub_date

1996-03-05 00:00:00

pages

1977-81

issue

eissn

0027-8424

issn

1091-6490

journal_volume

pub_type

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Nucleotide binding-promoted conformational changes release a nonnative polypeptide from the Escherichia coli chaperonin GroEL.