Although small, bacteria have demonstrated astonishing 'intelligence' in their battle against viruses. On the 17th, it was learned from China Pharmaceutical University that Professor Xiao Yibei's team from the National Key Laboratory of Multi target Natural Medicine and relevant domestic research institutions have discovered a new bacterial immune system CRISPR-AAD. The system uses up the energy molecule ATP inside bacteria to prevent virus spread. This study reveals the unique connection between bacterial immune system and energy metabolism, and provides new ideas for the prevention and treatment of bacterial resistance to viral infections. The relevant results were recently published in the international academic journal Science. Regularly spaced clustered short palindromic repeat sequences (CRISPR) are the acquired immune system of bacteria, with 60% of bacteria containing the CRISPR system. There are also many types of this system, some of which can cleave the DNA of bacteriophages and kill them Xiao Yibei told reporters that CRISPR Cas is a natural immune system that exists in bacteria and archaea. It will act like a 'scout', using RNA to detect foreign invaders such as virus DNA or RNA, and launch attacks to protect itself. Among all known CRISPR Cas systems, type III is the most complex Xiao Yibei said that in this study, the team found through bioinformatics analysis that some type III CRISPR Cas systems lack traditional nucleic acid cleavage functions, but carry CRISPR coupled deaminase CAAD and nucleotide hydrolase Nudix. Xiao Yibei introduced that the team later found that when the CRISPR-AAD system detects virus invasion, it synthesizes special messenger molecules such as cA3, cA4, and cA6. Among them, cA4 and cA6 can activate CAAD protein, causing it to deplete the molecule adenosine triphosphate (ATP) that provides energy inside the bacteria and convert it into hypoxanthine triphosphate (ITP). This conversion will quickly deplete bacterial energy. And ITP carries toxicity, which can inhibit bacterial growth, prevent virus replication and spread. This is equivalent to cells dying together with viruses through 'suicide', thus preserving other bacteria from being infected by viruses Xiao Yibei said, but it's not over yet. After the virus is cleared, bacteria use Nudix to break down harmful ITP into harmless inosinic acid (IMP), thus restoring normal growth. This detoxification mechanism ensures the survival of bacterial populations. Xiao Yibei believes that the discovery of the anti infection mechanism of CRISPR-AAD provides a new perspective for understanding the diversity and complexity of bacterial immune systems. A thorough analysis of this mechanism not only helps to promote the development of gene editing and biomedical technology, but also provides important ideas for the research and development of related anti infective drugs. (New Society)