How RNA and Amino Acids May Have Linked on Early Earth

07 Sep 2025 GS 3 Science & Technology

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Background

Life today depends on partnership between RNA (stores instructions) and proteins (do the work in cells).

To make proteins, amino acids (building blocks) need to be arranged according to RNA’s instructions.

But here’s the problem: the enzymes that help connect amino acids to RNA are themselves proteins. So which came first — proteins or RNA? That’s been a long-standing puzzle.

RNA → stores genetic instructions.
Proteins → perform structural, catalytic, and regulatory functions.

Modern protein synthesis:
- Amino acids are loaded onto RNA adapters by enzymes (proteins).
- Ribosome translates RNA into proteins.

**New Study (Published in Nature, University College London)**

Discovery: Amino acids can attach to RNA without enzymes, using aminoacyl-thiols.
Conditions: Plain water, neutral pH, possible in early Earth ponds or frozen pools.
Unexpected Selectivity:
- RNA (normally less reactive) preferred over other molecules.
- Amino acids latched precisely onto RNA ends, similar to modern biology.

Significance of Findings

Bridges RNA and Proteins
- Shows direct chemical “conversation” between RNA and amino acids without intermediaries.
- Provides a plausible path for primitive protein translation.
Two-Stage Switch
- With one form (thioesters), amino acids attach to RNA.
- With another form (thioacids), they start joining together into small chains (peptides).
- This looks like a primitive version of modern protein-making.
- Aminoacyl-thiols: Guide amino acids to RNA (charging step).
- Thioacids: Promote peptide bond formation (linking step).
Plausible Early Earth Chemistry
- Aminoacyl-thiols could form from simple precursors (nitriles, thiols).
- Reactions accelerated in frigid, concentrated pools → realistic prebiotic environment.

Implications for Origin of Life

Supports a gradual evolution of complexity:
- Short peptides → longer coded proteins.
- RNA gradually gains control over peptide synthesis.
Suggests RNA World Hypothesis may have naturally transitioned into an RNA–Protein World.
Challenges earlier studies that considered peptides and nucleotides separately.

Limitations & Next Steps

Only short peptides formed so far.
How to extend peptide chains in prebiotic conditions.

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