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Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Engineering an inward proton transport from a bacterial sensor rhodopsin
Akira Kawanabe1, Yuji Furutani, Kwang-Hwan Jung
1Department of Materials Science and Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
Journal of the American Chemical Society
|October 24, 2009
Summary
Researchers engineered an inward-directed proton pump from a bacterial rhodopsin using a single amino acid change. This breakthrough in bioengineering creates a novel inward proton transport mechanism, unlike typical proton pumps.
Area of Science:
- Biochemistry
- Molecular Biology
- Bioengineering
Background:
- Proton pumps are essential for generating proton motive force, crucial for ATP synthesis.
- Bacteriorhodopsin (BR) is a well-studied outward-directed, light-driven proton pump.
- Engineering inward-directed proton pumps presents challenges due to the need to prevent reverse transport.
Purpose of the Study:
- To engineer an inward-directed proton pump from a bacterial rhodopsin.
- To investigate the role of specific amino acid residues in controlling proton transport directionality.
- To explore novel bioengineering strategies for membrane transport proteins.
Main Methods:
- Site-directed mutagenesis of Anabaena sensory rhodopsin (ASR).
- Spectroscopic analysis using Fourier-transform infrared (FTIR) spectroscopy.
- Characterization of proton transport activity and directionality.
Main Results:
- A single amino acid replacement (Asp217 to Glu) in ASR engineered inward proton transport activity.
- The engineered ASR functions as a light-driven inward proton pump.
- FTIR spectra indicated increased proton affinity for the mutated Glu217 residue, explaining the reversed directionality.
Conclusions:
- Inward-directed proton transport can be achieved through targeted amino acid substitution in bacterial rhodopsins.
- The cytoplasmic domain plays a critical role in regulating proton pump directionality.
- This study provides a novel platform for engineering membrane transport proteins with specific functions.
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