Changing the tracks: screening for electron transfer proteins to support hydrogen production

Area of Science:

• Biochemistry
• Photosynthesis
• Algal Metabolism

Background:

• Ferredoxins are crucial electron carriers in biological systems.
• In Chlamydomonas reinhardtii, photosynthetic ferredoxin PetF primarily interacts with ferredoxin-NADP+ reductase (FNR), not hydrogenases (HydA1, HydA2).
• The specific electron donors for algal hydrogenases remain largely uncharacterized.

Purpose of the Study:

• To identify alternative electron donors for Chlamydomonas reinhardtii hydrogenases HydA1 and HydA2.
• To investigate the substrate specificity of uncharacterized ferredoxins (Fdx7, Fdx8, Fdx10, Fdx11).
• To explore the potential of synthetic electron donors for hydrogenase reduction.

Main Methods:

• Screening of uncharacterized ferredoxins (Fdx7-11) for their ability to reduce hydrogenases.
• Assessing ferredoxin affinity in the presence and absence of ferredoxin-NADP+ reductase (FNR).
• Utilizing synthetic iron-sulfur cluster-binding maquettes as artificial electron donors.

Main Results:

• Ferredoxin 7 (Fdx7) demonstrated a higher affinity for reducing hydrogenase 1 (HydA1) compared to FNR.
• Uncharacterized ferredoxins were evaluated as potential electron donors for hydrogenases.
• Synthetic FeS-cluster-binding maquettes successfully reduced hydrogenases when supplied with NADPH.

Conclusions:

• Ferredoxin 7 is a potential physiological electron donor for hydrogenase 1 in Chlamydomonas reinhardtii.
• This study expands the known electron transfer network in algal metabolism.
• Findings support the engineering of artificial electron donors for targeted enzyme reduction.