Intramolecular seal against proton backflow in bacteriorhodopsin
Zhong Ren1,2
1Department of Chemistry, University of Illinois Chicago, Chicago, IL 60607, USA.
Iscience
|May 6, 2026
Summary
Light-driven proton pumps use an intramolecular seal to prevent backflow. This study visualizes intermediate states of bacteriorhodopsin, revealing the mechanism of this crucial proton transport.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Microorganisms utilize light energy to create electrochemical gradients via proton pumps.
- These pumps must overcome molecular-level backflow to maintain the gradient.
Purpose of the Study:
- To elucidate the molecular mechanism of proton pumping in bacteriorhodopsin.
- To resolve structural heterogeneity and visualize intermediate states of the proton pump.
Main Methods:
- Utilized femtosecond serial crystallography to analyze structural data.
- Unscrambled mixed structural signals to improve electron density maps.
Main Results:
- Provided clear visualization of isolated intermediate states (I to M) in bacteriorhodopsin.
- Revealed the motion of an intramolecular seal that partitions cellular channels.
- Demonstrated how the seal prevents proton backflow.
Conclusions:
- The intramolecular seal is key to preventing proton backflow during light-driven pumping.
- Understanding bacteriorhodopsin's mechanism offers insights into bioenergetics and ion transport.
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