Toward life with a 19-amino acid alphabet through generative artificial intelligence design
Summary
Because all known living organisms are made from at least 20 canonical amino acids, the feasibility of life using a more simplified alphabet remains unclear. In this work, we leveraged computational design and synthetic biology to explore building a cell from a 19-amino acid alphabet. Initial analyses suggested that isoleucine (Ile) may be dispensable, which we confirmed by directly replacing Ile residues in essential proteins in Escherichia coli. Critically, protein language models and st
Content
# Toward life with a 19-amino acid alphabet through generative artificial intelligence design
*Published: 2026 Apr 30*
Because all known living organisms are made from at least 20 canonical amino
acids, the feasibility of life using a more simplified alphabet remains unclear.
In this work, we leveraged computational design and synthetic biology to explore
building a cell from a 19-amino acid alphabet. Initial analyses suggested that
isoleucine (Ile) may be dispensable, which we confirmed by directly replacing
Ile residues in essential proteins in Escherichia coli. Critically, protein
language models and structure-based models were necessary to redesign functional
Ile-less proteins in most cases. We systematically replaced all 382 Ile residues
from the ribosome and combined 21 redesigned subunits at a native genomic locus
to produce a viable, evolutionarily stable cell. This work provides a roadmap to
create the first 19-amino acid organism since early evolution.
DOI: 10.1126/science.aeb5171