In vitro hydrogen production by mammal [FeFe]-hydrogenase-like protein

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Exogenous hydrogen gas (H₂) influences mammalian physiological and pathological responses.
• The endogenous production of H₂ in mammalian cells remains largely uncharacterized.

Purpose of the Study:

• To investigate the potential for endogenous H₂ production in mammalian cells.
• To identify proteins involved in H₂ metabolism in eukaryotes.

Main Methods:

• Expression of recombinant human (Homo sapiens) nuclear prelamin recognition factor-like protein (HsIOP1) and pig (Sus scrofa) cytosolic iron-sulfur assembly component 3 (SsCIAO3) in a prokaryotic system.
• In vitro enzymatic assays to detect H₂ production.
• Transcriptome database analysis to assess protein distribution.
• Sequence and structural analysis of identified proteins.
• Phylogenetic analysis to infer evolutionary relationships.

Main Results:

• Recombinant HsIOP1 and SsCIAO3, belonging to the [FeFe]-hydrogenase-like protein family, demonstrated potential H₂ production activity in vitro under anaerobic conditions.
• Narf-like proteins, including HsIOP1 and SsCIAO3, are widely expressed in human and pig tissues.
• Structural analysis suggests these proteins contain a [4Fe4S] cluster, characteristic of hydrogenases.
• Phylogenetic analysis indicates hydrogen metabolism may have been overlooked in eukaryotic evolution.

Conclusions:

• Nuclear prelamin recognition factor (Narf)-like proteins (HsIOP1 and SsCIAO3) possess hydrogenase activity, suggesting endogenous H₂ production in eukaryotes.
• The widespread presence of these proteins implies that H₂ production could be a universal phenomenon in eukaryotic organisms.
• This discovery opens new avenues for understanding hydrogen metabolism in eukaryotes and its evolutionary history.