New study suggests LUCA was a metal-catalyzed chemical system, not a true cell
A research team proposes that the last universal common ancestor was a partly chemical, partly organic entity in hydrothermal vents, meaning life may have originated twice.
Evolutionary biologist Bill Martin and his collaborators argue that the conventional picture of LUCA as a fully functional microbe is misleading; instead it was a hybrid of organic molecules and mineral catalysts formed in hydrothermal vent environments. By mathematically back-extrapolating modern genomes, they identified missing enzymes in the metabolic networks of the earliest bacterial and archaeal ancestors, concluding that LUCA possessed genes for only about half of metabolism.
The study suggests that metals like nickel, iron, cobalt and palladium present in vent minerals supplied the catalytic activity absent from proteins, and that phosphite could have acted as an early energy source. Experimental results demonstrate palladium can catalyze phosphite-driven reactions, supporting a metal-based proto-metabolism. The researchers maintain that a primitive nucleic-acid based genetic system existed alongside this chemistry, allowing enzymes and metabolism to co-evolve. If validated, the findings imply two separate lineages of life emerged from a common, non-living chemical system, reshaping the debate over the origin of life.
Why it matters
Understanding LUCA's nature could rewrite the story of how life first emerged on Earth.
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