Graduate Students Mini Symposium VI - 2026

13:15 h Marcello Herzog - ENG Rebelein

The nitrogenase-like enzyme of Endomicrobium proavitum incorporates molybdenum and an unknown ligand and reduces sulfur compounds

Bioavailable nitrogen sources are essential for all life. However, converting molecular dinitrogen (N₂) to bioavailable ammonia (NH₃) is energy (ATP)-intensive and catalyzed by the complex metalloenzyme nitrogenase. One section of the large nitrogenase tree are nitrogen-fixation-like (Nfl) enzymes, which are structural homologs of nitrogenases with diverse functions. The Nfl-enzymes are gaining increasing attention because they catalyze novel reduction reactions. My research focuses on the structural and biochemical characterization of one specific Nfl-enzyme from Endomicrobium proavitum that has been shown to reduce N₂ to NH₃ in vivo. In my presentation, I will discuss our surprising findings in structure and function.

13:45 h Giuseppe Peyroche - MPRG Preiner

A mineral- and cofactor-assisted, non-enzymatic methyl branch of the reductive acetyl-CoA pathway

The reaction between CO₂ and H₂ is the centre of the most ancient form of carbon metabolism, the reductive acetyl-CoA pathway. There are parallels between hydrothermal, mineral-assisted CO₂ fixation with H₂ and the enzymatically catalysed steps of the reductive acetyl-CoA pathway, which is considered a possible hint towards the abiotic beginnings of metabolism. We show that formic acid can react with the folate carrier tetrahydrofolic acid under hydrothermal conditions to form an activated methyl-group as 5-methyltetrahydrofolic acid, mimicking the pathway and showing how the interplay of geochemical processes and organic cofactors is enough to drive forward protometabolism.