Scientists have taken a major step in rewriting the rules of life by engineering bacteria to function with just 19 amino acids instead of the standard 20.
All life on Earth depends on the same molecular system: cells use 20 amino acids to build proteins, which carry out essential biological functions. But researchers have now shown that one of these building blocks can be removed — without breaking a key cellular process.
Experts say the achievement is comparable to rewriting part of a complex text while removing a commonly used letter, yet still keeping the meaning intact.
Rethinking life’s “alphabet”
The research focuses on altering the genetic code — the instructions cells use to assemble proteins. Scientists have previously modified DNA, but changing the amino acid set itself has long been considered too risky, as even small changes can disrupt protein function.
Led by synthetic biologist Harris Wang at Columbia University, the team initially struggled. Early attempts to replace the amino acid isoleucine caused many proteins to fail.
Progress came with advances in artificial intelligence. Tools such as AlphaFold helped predict protein structures and identify alternative sequences that could still function properly.
Targeting the cell’s core machinery
Rather than attempting to redesign every protein in the bacterium Escherichia coli, researchers focused on the ribosome — the molecular machine responsible for building proteins.
The ribosome is central to life, translating genetic instructions into functional molecules. Demonstrating that it can operate without one amino acid suggests that more extensive redesigns may be possible.
“This shows it’s actually achievable,” said Julius Fredens, a synthetic biologist not involved in the study.
What it could mean
The findings could open new possibilities in synthetic biology, allowing scientists to design organisms with novel capabilities not found in nature.
It may also provide clues about early life on Earth, which might have relied on a simpler set of molecular components before evolving into the complex systems seen today.
While still at an early stage, the work suggests that the fundamental “alphabet” of life is more flexible than previously believed.
Source: BBC article
