Scientists from Columbia University, Massachusetts Institute of Technology, and Harvard University in the United States have designed a genetically engineered E. coli strain Ec19 using generative artificial intelligence (AI) and deep learning models. It survives on only 19 amino acids, not the usual 20. This work has laid the blueprint for creating cells that surpass natural abilities. The relevant results were published in the latest issue of the journal Science. Scientists have streamlined the genome by removing DNA fragments that encode sequences similar to other amino acids. But most scientists have not touched upon the "classic" 20 amino acids, as even fine-tuning the protein amino acid sequence could disrupt its function. Although scientists have discovered over 500 different amino acids in nature, living organisms only use the standardized 20 when synthesizing proteins, as confirmed by large-scale genetic research. However, scientists believe that before single celled organisms became the last common ancestor, early life forms likely used fewer amino acids than those seen today. Computational studies have shown that with only 9 to 12 amino acids, almost all known protein morphologies can be constructed. This raises an intriguing question: can life function normally without using one amino acid? In the latest study, the team first analyzed 20 amino acids to find the most easily replaceable one. Isoleucine thus entered people's field of vision because it is chemically very similar to another amino acid - valine. So, they followed a cautious and gradual "design build test" framework to explore whether they could create a living cell free of isoleucine. To improve the results, the team sought the help of AI to select the best substitute for missing amino acids based on the sequence environment, ensuring that the protein does not fold or collapse incorrectly. They redesigned ribosomes capable of producing 52 isoleucine free proteins, and ultimately assembled 21 of the reconstructed components into a single E. coli strain named Ec19. The results showed that the obtained Ec19 genome remained stable and reproduced for more than 450 generations at almost normal bacterial speeds in the laboratory. Whole genome sequencing also did not find any signs of Ec19 attempting to recover isoleucine and return to the 20 amino acid system. The team believes that with the advancement of genome scale modeling and DNA synthesis technology, scientists will be able to create cells with new characteristics by replacing amino acids, test a large number of engineered genomes, and continuously break through the boundaries of synthetic biology. (Looking into the New Era)