Biochemistry & Organic Chemistry

What Powered the Earth’s Earliest Life?

By Keith Cowing

Press Release

UCSD

June 12, 2026

Filed under biochemistry, genomics, guanosine‑triphosphate (GTP), origin of life, PNAS, ribozyme, RNA, RNA polymerization, UCSD

What Powered the Earth’s Earliest Life? — Schematic of the selection step in the doped in emulsio selection. The oil phase is depicted as a gray background and the aqueous droplet as white circle. The droplet contains two RNA molecules: The doped library of GTR1 variants (Left) contained a partially randomized sequence (light blue) and its 3′-terminus (dark blue) was base paired to the polymerase ribozyme (Right; gray). The GTP synthase library was challenged to catalyze the reaction between 6sG and cTmp to 6sGTP (top red arrow). The chemical structures of 6sG, cTmp, and 6sGTP are shown. Reaction conditions were 1 mM guanosine, 50 mM Na3cTmp, 150 mM MgCl2, 200 mM KCl, 50 mM Tris/HCl pH 8.0 at 22 °C for 1 h. The 6sGTP was then used by the polymerase ribozyme to tag the 3′-terminus of the GTR library (dark blue and bottom red arrow). The GTR1 library was truncated internally (*) to reduce the total length of the partially randomized region to 116 nucleotides. The library 3′-terminus (dark blue) was processed by an M1 RNase P ribozyme for homogeneous 3′-ends (SI Appendix, Fig. S3). Two polymerase ribozyme variants were used, one of them with sevenfold lower activity where a U in the NTP binding loop at position 156 was replaced by a C (bold dark gray). The diameter of the aqueous droplets was adjusted between ~150 nm and ~400 nm by modifications to the emulsification procedure. — PNAS

Early biological systems likely relied on RNA molecules to copy themselves and drive simple chemical reactions.

Any system that could generate guanosine‑triphosphate (GTP) — which is necessary for RNA synthesis — from prebiotic chemicals would gain a crucial advantage toward self‑replication. Now researchers from the University of California San Diego report a version of an RNA enzyme (ribozyme) that makes GTP synthesis more efficient than its predecessor.

By placing a library of about 100,000,000,000,000 mutated ribozymes into nano-droplets of water-in-oil emulsions, researchers were able to metabolically couple GTP synthesis to RNA polymerization and identify which mutations produced the most GTP. The most productive ribozymes produced about 10 times more GTP than their predecessor. This is enough to drive RNA polymerization, where separate RNA monomers are linked together into polymers – a crucial step in the development of life.

The study was published on June 9, 2026 in Proceedings of the National Academy of Sciences (PNAS). Authors are Xu Han, Zoe Pepper, Joshua Arriola and Ulrich Müller. Their research was funded by the National Aeronautics and Space Administration Interdisciplinary Consortium for Astrobiology Research (ICAR 80NSSC21K0596).

A GTP synthase ribozyme with increased GTP turnover, PNAS (open access)

Astrobiology

Keith Cowing

Biologist, Explorers Club Fellow, ex-NASA Space Biologist and Payload integrator, Editor of NASAWatch.com and Astrobiology.com, Lapsed climber, Explorer, Synaesthete, Former Challenger Center board member 🖖🏻

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