The molecular chaperone Hsc70 assists the in vitro folding of the N- terminal nucleotide-binding domain of the cystic fibrosis transmembrane conductance regulator

Elizabeth Strickland, Bao He Qu, Linda Millen, Philip J. Thomas

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

The most common disease-causing mutation in the cystic fibrosis transmembrane conductance regulator is a single amino acid deletion (ΔF508) in the N-terminal cytosolic nucleotide-binding domain (NBD1). This mutation has previously been shown to be a temperature-sensitive folding mutation that alters the folding pathway but not the native state stability of the isolated domain (Qu, B.-H., and Thomas, P. J. (1996) J. Biol. Chem. 271, 7261-7264). Here we provide evidence that the molecular chaperone Hsc70 productively interacts with NBD1 to increase the folding yield of the domain and inhibit off-pathway associations leading to the formation of high molecular weight aggregates. Furthermore, we have sublocalized a region within NBD1 where Hsc70 binds. Notably, inhibition of NBD1 aggregation is not dependent upon the presence of Hsc70 in the early stages of folding, indicating that the chaperone may act on a folding intermediate. In the presence of K+ and Mg2+-ATP, conditions where Hsp70 binds substrate rapidly and can release it, Hsc70 is less effective at inhibiting NBD1 aggregation. Thus, the rate of release of unfolded substrate is an important factor in preventing aggregation and promoting folding of the domain. These results demonstrate that Hsc70 promotes the otherwise inefficient folding of ΔF-NBD1 and provide insight into the mechanisms by which molecular chaperones assist proteins in folding.

Original languageEnglish (US)
Pages (from-to)25421-25424
Number of pages4
JournalJournal of Biological Chemistry
Volume272
Issue number41
DOIs
StatePublished - Oct 10 1997

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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