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Structural pathway of regulated substrate transfer and threading through an Hsp100 disaggregase

DOI: 10.1126/sciadv.1701726 DOI Help

Authors: Celia Deville (Birkbeck, University of London) , Marta Carroni (Birkbeck, University of London) , Kamila B. Franke (German Cancer Research Center) , Maya Topf (Birkbeck, University of London) , Bernd Bukau (German Cancer Research Center) , Axel Mogk (German Cancer Research Center) , Helen R. Saibil (Birkbeck, University of London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Science Advances , VOL 3

State: Published (Approved)
Published: August 2017
Diamond Proposal Number(s): 14704

Open Access Open Access

Abstract: Refolding aggregated proteins is essential in combating cellular proteotoxic stress. Together with Hsp70, Hsp100 chaperones, including Escherichia coli ClpB, form a powerful disaggregation machine that threads aggregated polypeptides through the central pore of tandem adenosine triphosphatase (ATPase) rings. To visualize protein disaggregation, we determined cryo–electron microscopy structures of inactive and substrate-bound ClpB in the presence of adenosine 5′-O-(3-thiotriphosphate), revealing closed AAA+ rings with a pronounced seam. In the substrate-free state, a marked gradient of resolution, likely corresponding to mobility, spans across the AAA+ rings with a dynamic hotspot at the seam. On the seam side, the coiled-coil regulatory domains are locked in a horizontal, inactive orientation. On the opposite side, the regulatory domains are accessible for Hsp70 binding, substrate targeting, and activation. In the presence of the model substrate casein, the polypeptide threads through the entire pore channel and increased nucleotide occupancy correlates with higher ATPase activity. Substrate-induced domain displacements indicate a pathway of regulated substrate transfer from Hsp70 to the ClpB pore, inside which a spiral of loops contacts the substrate. The seam pore loops undergo marked displacements, along with ordering of the regulatory domains. These asymmetric movements suggest a mechanism for ATPase activation and substrate threading during disaggregation.

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios I-Titan Krios I at Diamond

Other Facilities: Krios microscope at SciLifeLab, Univeristy of Stockholm

Added On: 15/08/2017 18:35

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