Unveiling a hydrogen-controlled nano-switch in electron transport proteins

Researchers at Osaka University have unveiled a groundbreaking mechanism that controls the electric potential of a universal "electron carrier" protein involved in redox reactions - processes critical for energy generation in living organisms. By determining the precise 3D structure of ferredoxin, including hydrogen atoms, the team identified a "nano-switch" mechanism where the presence or absence of a single hydrogen atom can dramatically alter the protein's electric potential.

The study used the Ibaraki Biological Crystal Diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC) to map the 3D structure of ferredoxin, a protein containing iron-sulfur clusters known to facilitate electron transfer in respiration and photosynthesis. Notably, visualizing hydrogen atoms within protein structures is exceptionally rare, representing less than 0.2% of all entries in the Protein Data Bank (PDB).

Through theoretical calculations based on experimental data, researchers pinpointed aspartic acid 64, an amino acid residue distant from the iron-sulfur cluster, as a critical component influencing electron transfer. This residue acts as a "switch" that regulates the redox stability of ferredoxin. The findings suggest that this mechanism is universal across various organisms.

"These results not only advance our understanding of biological redox reactions but also open the door to the development of ultra-sensitive oxygen and nitric oxide sensors, as well as innovative drugs," the researchers stated.

This study sheds light on how living systems achieve stability and precision in electron transport, offering a foundation for future technological and biomedical innovations.

Research Report:Protonation/deprotonation-driven switch for the redox stability of low potential [4Fe-4S] ferredoxin