The bacteria grew, thrived, and divided for hundreds of generations. But they were unlike any other living creatures on Earth. These synthetic cells, called Ec19, were the first to have had one protein “letter”—or amino acid—partially removed. All life today relies on a set of 20 amino acids to make proteins. Some exotic microbes can use 22 , but no one has yet found any that use less. Like letters in a book, amino acids string into coherent protein “sentences” that relay messages and do work within cells. Deleting an amino acid is like trying to type without the letter “e.” The text becomes gibberish. Or does it? A team from Columbia University and collaborators stripped one amino acid, isoleucine, from ribosomes in Escherichia coli (E. Coli) bacteria. These cellular machines translate DNA into proteins, and they’re among the most complex structures in cells. Deleting any amino acids could be catastrophic. But with some help from AI, Ec19 was born.…