Shiny metal catalysts at the origin of metabolism.

Metabolism is the reaction network that converts inanimate matter into living cells. There is no life without it. The network of approximately 400 enzymatic reactions that synthesize amino acids, nucleosides, and cofactors from compounds in the environment is conserved across life. Before enzymes, how did metabolism arise? The subsurface chemical environment of Earth's crust reveals clues. Serpentinizing (H2 producing) hydrothermal vents contain naturally deposited, shiny metals in their reduced (native) state and phosphite, a reduced form of phosphate. In the laboratory, native metal catalysts fix CO2, replacing hydrogenases, the acetyl-CoA pathway to pyruvate, the Krebs cycle, amino acid syntheses, NADH, and ferredoxin. Native metals also phosphorylate organic compounds in water using phosphite, uncovering a new source of energy at the origin of metabolism.