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Spatially and kinetically resolved changes in the conformational dynamics of the Hsp90 chaperone machine.

ABSTRACT: The highly conserved 90 kDa heat shock protein (Hsp90) chaperones use ATP to regulate the stability and activity of many signalling molecules like protein kinases and transcription factors. Studies using crystallography, electron microscopy and small-angle X-ray scattering yielded controversial results for the conformational states that these dimeric multidomain proteins assume while progressing through the ATPase cycle. To better understand the molecular mechanism of Hsp90 proteins, we studied the conformational dynamics of the Escherichia coli homologue HtpG in solution using amide hydrogen exchange mass spectrometry (HX-MS) and fluorescence spectroscopy. A conformation-sensitive fluorescent probe allowed to elucidate the ATPase cycle of HtpG. Continuous-labelling and pulse-labelling HX-MS experiments revealed major ATP-induced conformational changes throughout the protein that do not occur simultaneously, but progress surprisingly slow from the immediate nucleotide-binding site towards the N terminus and the middle domain. The conversion between the different conformational states is rate limiting for ATP hydrolysis, and the nucleotide-coordinating residue, Glu34, is important for the rate constant of conversion. Our findings, for the first time, allow to kinetically resolve changes in the conformational dynamics of individual structural elements of Hsp90.

SUBMITTER: Graf C

PROVIDER: S-EPMC2657576 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Spatially and kinetically resolved changes in the conformational dynamics of the Hsp90 chaperone machine.

Graf Christian C Stankiewicz Marta M Kramer Günter G Mayer Matthias P MP

The EMBO journal 20090122 5

The highly conserved 90 kDa heat shock protein (Hsp90) chaperones use ATP to regulate the stability and activity of many signalling molecules like protein kinases and transcription factors. Studies using crystallography, electron microscopy and small-angle X-ray scattering yielded controversial results for the conformational states that these dimeric multidomain proteins assume while progressing through the ATPase cycle. To better understand the molecular mechanism of Hsp90 proteins, we studied ...[more]

PMID: 19165152

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Project description:Hsp90 is a molecular chaperone essential for protein folding and activation in normal homeostasis and stress response. ATP binding and hydrolysis facilitate Hsp90 conformational changes required for client activation. Hsp90 plays an important role in disease states, particularly in cancer, where chaperoning of the mutated and overexpressed oncoproteins is important for function. Recent studies have illuminated mechanisms related to the chaperone function. However, an atomic resolution view of Hsp90 conformational dynamics, determined by the presence of different binding partners, is critical to define communication pathways between remote residues in different domains intimately affecting the chaperone cycle. Here, we present a computational analysis of signal propagation and long-range communication pathways in Hsp90. We carried out molecular dynamics simulations of the full-length Hsp90 dimer, combined with essential dynamics, correlation analysis, and a signal propagation model. All-atom MD simulations with timescales of 70 ns have been performed for complexes with the natural substrates ATP and ADP and for the unliganded dimer. We elucidate the mechanisms of signal propagation and determine "hot spots" involved in interdomain communication pathways from the nucleotide-binding site to the C-terminal domain interface. A comprehensive computational analysis of the Hsp90 communication pathways and dynamics at atomic resolution has revealed the role of the nucleotide in effecting conformational changes, elucidating the mechanisms of signal propagation. Functionally important residues and secondary structure elements emerge as effective mediators of communication between the nucleotide-binding site and the C-terminal interface. Furthermore, we show that specific interdomain signal propagation pathways may be activated as a function of the ligand. Our results support a "conformational selection model" of the Hsp90 mechanism, whereby the protein may exist in a dynamic equilibrium between different conformational states available on the energy landscape and binding of a specific partner can bias the equilibrium toward functionally relevant complexes.

Dataset Information

Spatially and kinetically resolved changes in the conformational dynamics of the Hsp90 chaperone machine.

Publications

Spatially and kinetically resolved changes in the conformational dynamics of the Hsp90 chaperone machine.

Similar Datasets

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