Nearly all known life builds proteins from the same alphabet of 20 canonical amino acids. Strung together in different orders, those building blocks form the proteins that make cells work. In a new Science study, researchers at Columbia University, the Massachusetts Institute of Technology and Harvard University used artificial-intelligence-guided protein design to test how much of that alphabet can be pared back: they engineered an Escherichia coli strain that survived after it was redesigned to not have a specific amino acid in its ribosomal proteins.
The team did not create a true 19-amino-acid organism. The engineered strain still uses the targeted amino acid, isoleucine, throughout most of its genome. But the result suggests that one of life’s most ancient and essential machines can tolerate at least partial simplification—and that AI may help biologists test the limits of life’s chemistry.
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