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Updated: Oct 9, 2025
07:38
Measuring In Vitro ATPase Activity for Enzymatic Characterization
Published on: August 23, 2016
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Structure and function of ClpXP, a AAA+ proteolytic machine powered by probabilistic ATP hydrolysis
Robert T Sauer1, Xue Fei1, Tristan A Bell1
1Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
Critical Reviews in Biochemistry and Molecular Biology
|December 20, 2021
Summary
ClpXP protease, comprising ClpX unfoldase and ClpP peptidase, is a well-studied AAA+ machine. This review details its structure, function, and ATP hydrolysis mechanisms, highlighting future research directions.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- ClpXP is an archetypal AAA+ protease composed of ClpX (an ATP-dependent unfoldase/translocase) and ClpP (a self-compartmentalized peptidase).
- It is the only AAA+ protease with available high-resolution structures, understood substrate recognition mechanisms, and extensive biochemical and genetic data.
- Single-molecule optical trapping has enabled direct visualization of substrate unfolding and translocation kinetics.
Purpose of the Study:
- To review the current understanding of ClpXP protease structure and function.
- To evaluate the distinct mechanisms of ATP hydrolysis (sequential vs. probabilistic).
- To identify and discuss key questions for future research in the ClpXP field.
Main Methods:
- High-resolution structural analysis.
- Biochemical assays to study protein unfolding and translocation.
- Genetic analyses to probe ClpXP function.
- Single-molecule optical trapping for kinetic studies.
Main Results:
- Detailed structural insights into the ClpXP complex.
- Elucidation of the molecular basis for protein substrate recognition.
- Comprehensive understanding of substrate unfolding and translocation kinetics.
- Evidence supporting both sequential and probabilistic models of ATP hydrolysis.
Conclusions:
- ClpXP represents a highly characterized AAA+ protease system.
- Further investigation is needed to fully resolve the mechanism of ATP hydrolysis.
- Open questions remain regarding ClpXP regulation and broader biological roles.
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