Transition metal nanoparticles: A missing link between early Earth and early life

• Applicants: Professor Dr. William Martin; Privatdozent Dr. Harun Tüysüz
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 404836229

Motivation for our proposal is the observation that naturally occurring chemical reactions in H2 producing hydrothermal vents bear detectable similarity to the core reactions of carbon and energy metabolism in anaerobic autotrophs that use the acetyl-CoA pathway of CO2 fixation, linking early earth chemistry to the metabolic reactions in primitive bacteria and archaea. In experiments from the previous funding period we have shown that two naturally existing transition metal minerals, awaruite (Ni3Fe) and magnetite (Fe3O4), synthesized as nanoparticular catalysts in Mülheim, will reproducibly convert 24 bar of H2 and CO2 (40:60) to formate (ca. 100 mM), acetate (ca. 100 micrometers), and pyruvate (ca. 40 micrometers) overnight at 100°C in the presence of water in small laboratory reactors in Düsseldorf. This highly specific product spectrum comprises the first three free intermediates of the acetyl-CoA pathway from H2 and CO2 to pyruvate. Although Ni3Fe and Fe3O4 can both fulfill the catalytic role of the 10-enzyme pathway, nitrogen incorporation to amino acids has proven more challenging, requiring us to explore alternative, more extreme conditions. Here we will investigate the ability of high pressure and high temperature conditions (up to 380°C and 800 bar) as well as mechanochemistry to generate suitably activated nitrogen species for incorporation into amino acids, the biochemical building blocks of bases. Having shown that transition metals can specifically catalyze the H2 dependent reduction of NAD+ to NADH, we will explore their ability to replace the most ancient and conserved function of flavin based electron bifurcation: the H2 dependent reduction of low potential ferredoxin. If successful, our findings will forge chemical evolutionary connections between the physiology of primitive autotrophs and naturally occurring heterogeneous catalysis in H2 producing hydrothermal vents, shedding light on longstanding questions of how metabolism, and life, could have arisen.

• DFG Programme: Research Grants