Life on Earth is built from a shared molecular system: 20 amino acids that cells use to construct proteins. Now, scientists are testing how flexible that system really is.
Researchers have successfully engineered bacteria to function with just 19 amino acids, removing one component from what has long been considered a universal biological “alphabet”.
The achievement suggests that life’s basic rules may be less fixed than previously thought.
The work, led by Harris Wang at Columbia University, initially faced major challenges. Early attempts to replace the amino acid isoleucine caused many proteins to fail.
Progress became possible with advances in artificial intelligence. Tools such as AlphaFold helped researchers predict how proteins fold and identify alternative sequences that could still function.
Instead of redesigning every protein in Escherichia coli, the team focused on the ribosome — the cell’s core machinery responsible for building proteins.
If such a critical system can operate without one amino acid, scientists say similar approaches could eventually apply more broadly.
Experts suggest the research could lead to engineered organisms with new capabilities, as well as insights into how early life might have functioned with simpler molecular systems.
