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Two-step activation mechanism of the ClpB disaggregase for sequential substrate threading by the main ATPase motor

AAA+ proteins form asymmetric hexameric rings that hydrolyze ATP and thread substrate proteins through a central channel via mobile substrate-binding pore loops. Understanding how ATPase and threading activities are regulated and intertwined is key to understanding the AAA+ protein mechanism. We stu...

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Bibliographic Details
Main Authors: Deville, Célia (Author) , Franke, Kamila B. (Author) , Mogk, Axel (Author) , Bukau, Bernd (Author) , Saibil, Helen R. (Author)
Format: Article (Journal)
Language:English
Published: 18 June 2019
In: Cell reports
Year: 2019, Volume: 27, Issue: 12, Pages: 3433-3446.e4
ISSN:2211-1247
DOI:10.1016/j.celrep.2019.05.075
Online Access:Verlag, Volltext: https://doi.org/10.1016/j.celrep.2019.05.075
Verlag: https://www.sciencedirect.com/science/article/pii/S2211124719307041
Verlag, Volltext: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6593972/
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Author Notes:Célia Deville, Kamila Franke, Axel Mogk, Bernd Bukau, and Helen R. Saibil
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Summary:AAA+ proteins form asymmetric hexameric rings that hydrolyze ATP and thread substrate proteins through a central channel via mobile substrate-binding pore loops. Understanding how ATPase and threading activities are regulated and intertwined is key to understanding the AAA+ protein mechanism. We studied the disaggregase ClpB, which contains tandem ATPase domains (AAA1, AAA2) and shifts between low and high ATPase and threading activities. Coiled-coil M-domains repress ClpB activity by encircling the AAA1 ring. Here, we determine the mechanism of ClpB activation by comparing ATPase mechanisms and cryo-EM structures of ClpB wild-type and a constitutively active ClpB M-domain mutant. We show that ClpB activation reduces ATPase cooperativity and induces a sequential mode of ATP hydrolysis in the AAA2 ring, the main ATPase motor. AAA1 and AAA2 rings do not work synchronously but in alternating cycles. This ensures high grip, enabling substrate threading via a processive, rope-climbing mechanism.
Item Description:Published online 18 June 2019
Gesehen am 15.01.2020
Physical Description:Online Resource
ISSN:2211-1247
DOI:10.1016/j.celrep.2019.05.075

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