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Cell. 2013 Oct 24;155(3):636-646. doi: 10.1016/j.cell.2013.09.022. Epub 2013 Oct 24.

The ClpXP protease unfolds substrates using a constant rate of pulling but different gears.

Author information

1
Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, CA 94720, USA.
2
Department of Chemistry, University of California, Berkeley, CA 94720, USA.
3
QB3 Institute, University of California, Berkeley, CA 94720, USA.
4
Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA.
5
Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA.
6
Department of Physics, University of California, Berkeley, CA 94720, USA.
7
Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
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Contributed equally

Abstract

ATP-dependent proteases are vital to maintain cellular protein homeostasis. Here, we study the mechanisms of force generation and intersubunit coordination in the ClpXP protease from E. coli to understand how these machines couple ATP hydrolysis to mechanical protein unfolding. Single-molecule analyses reveal that phosphate release is the force-generating step in the ATP-hydrolysis cycle and that ClpXP translocates substrate polypeptides in bursts resulting from highly coordinated conformational changes in two to four ATPase subunits. ClpXP must use its maximum successive firing capacity of four subunits to unfold stable substrates like GFP. The average dwell duration between individual bursts of translocation is constant, regardless of the number of translocating subunits, implying that ClpXP operates with constant "rpm" but uses different "gears."

PMID:
24243020
PMCID:
PMC3901371
DOI:
10.1016/j.cell.2013.09.022
[Indexed for MEDLINE]
Free PMC Article
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