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Updated: May 24, 2026
10:41
Detection of Toxin Translocation into the Host Cytosol by Surface Plasmon Resonance
Published on: January 3, 2012
Ratcheting up protein translocation with anthrax toxin
Geoffrey K Feld1, Michael J Brown, Bryan A Krantz
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Protein Science : a Publication of the Protein Society
|March 1, 2012
Summary
Cellular nanomachines use a molecular ratchet mechanism to translocate proteins. This process involves a cyclical order-to-disorder thermodynamic mechanism, similar to a heat-engine cycle, driving protein movement.
Area of Science:
- Molecular biology
- Biophysics
- Cellular mechanics
Background:
- Cellular nanomachines facilitate directed biopolymer movement within aqueous cytosol and lipid bilayers.
- Protein translocation by biological nanomachines (translocases) often necessitates substrate protein unfolding.
- The anthrax toxin system serves as a model for studying protein translocation mechanisms.
Purpose of the Study:
- To elucidate the molecular mechanisms of nanomachine-catalyzed biopolymer transport.
- To highlight the role of molecular ratchets in protein translocation.
- To explore the application of the anthrax toxin translocation model to broader systems.
Main Methods:
- Investigation of molecular components like adjustable clamps, levers, and adaptors in nanomachine function.
- Analysis of the anthrax toxin system as a model for protein translocation.
- Characterization of proton-gradient-driven translocation and associated ratchet mechanisms.
Main Results:
- A cyclical thermodynamic order-to-disorder mechanism is central to protein translocation.
- Peptide substrates bind to molecular clamps with adjustable affinities.
- Proton-gated switching of clamps drives substrate compression and subsequent expansion, regaining conformational entropy.
Conclusions:
- Proton-gradient-driven translocation and ratchet mechanisms are likely broadly applicable to biological systems.
- The identified cyclical thermodynamic mechanism provides insight into how nanomachines overcome entropic challenges in protein transport.
- Understanding these mechanisms is crucial for comprehending cellular protein trafficking and nanomachine function.
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