Mapping the conformation of a client protein through the Hsp70 functional cycle

The 70 kDa heat shock protein (Hsp70) chaperone system is ubiquitous, highly conserved, and involved in a myriad of diverse cellular processes. Its function relies on nucleotide-dependent interactions with client proteins, yet the structural features of folding-competent substrates in their Hsp70-bo...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2015-08, Vol.112 (33), p.10395-10400
Main Authors: Sekhar, Ashok, Rosenzweig, Rina, Bouvignies, Guillaume, Kay, Lewis E.
Format: Article
Language:English
Subjects:
Adenosine Diphosphate - chemistry
Adenosine triphosphatase
Adenosine Triphosphate - chemistry
Binding Sites
Biochemistry, Molecular Biology
Biological Sciences
Cellular biology
Diffusion
E coli
Escherichia coli
Escherichia coli - metabolism
Escherichia coli Proteins - chemistry
Heat shock proteins
HSP70 Heat-Shock Proteins - chemistry
Humans
Hydrolysis
Kinetics
Life Sciences
Magnetic Resonance Spectroscopy
Molecular Chaperones
Protein Folding
Protein Structure, Secondary
Spectrum analysis
Structural Biology
Substrate Specificity
Telomeric Repeat Binding Protein 1 - chemistry
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Summary:The 70 kDa heat shock protein (Hsp70) chaperone system is ubiquitous, highly conserved, and involved in a myriad of diverse cellular processes. Its function relies on nucleotide-dependent interactions with client proteins, yet the structural features of folding-competent substrates in their Hsp70-bound state remain poorly understood. Here we use NMR spectroscopy to study the human telomere repeat binding factor 1 (hTRF1) in complex withEscherichia coliHsp70 (DnaK). In the complex, hTRF1 is globally unfolded with up to 40% helical secondary structure in regions distal to the binding site. Very similar conformational ensembles are observed for hTRF1 bound to ATP-, ADP- and nucleotide-free DnaK. The patterns in substrate helicity mirror those found in the unfolded state in the absence of denaturants except near the site of chaperone binding, demonstrating that DnaK-bound hTRF1 retains its intrinsic structural preferences. To our knowledge, our study presents the first atomic resolution structural characterization of a client protein bound to each of the three nucleotide states of DnaK and establishes that the large structural changes in DnaK and the associated energy that accompanies ATP binding and hydrolysis do not affect the overall conformation of the bound substrate protein.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1508504112