Effects of Active-Center Reduction of Plant-Type Ferredoxin on Its Structure and Dynamics: Computational Analysis...

Area of Science:

• Biochemistry
• Structural Biology
• Photosynthesis Research

Background:

• Plant-type ferredoxins (Fds) are crucial for light-induced electron transfer in photosynthesis, utilizing a [2Fe-2S] cluster.
• Existing structural data for Fds are largely static, limiting understanding of their dynamic behavior during electron transfer.

Purpose of the Study:

• To investigate the structural and dynamic effects of active-center reduction on plant-type ferredoxins.
• To elucidate the electron transfer mechanisms by analyzing changes in Fd structure and dynamics.

Main Methods:

• Constructed oxidized and reduced Fd model systems from the crystal structure of *Chlamydomonas reinhardtii* Fd1.
• Performed three 200 ns molecular dynamics simulations for both oxidized and reduced Fd states.
• Obtained force field parameters for active centers using quantum chemical calculations.

Main Results:

• No significant global conformational differences were observed between oxidized and reduced Fds.
• Active-center reduction altered the hydrogen-bond network and residue compactness around the active site.
• Increased flexibility of the Phe61 side chain was noted upon reduction, crucial for Fd-protein interactions.

Conclusions:

• Computational simulations reveal that ferredoxin reduction induces localized dynamic changes rather than global structural shifts.
• These dynamic alterations, particularly in key residues like Phe61, are vital for mediating efficient electron transfer to target proteins.
• The study provides valuable insights into the dynamic aspects of ferredoxin function in photosynthetic electron transport chains.