In situ chemoproteomic profiling reveals itaconate inhibits de novo purine biosynthesis in pathogens.

Itaconate serves as an immune-specific metabolite that regulates gene transcription and metabolism in both host and pathogens. S-itaconation is a post-translational modification that regulates immune response; however, its antimicrobial mechanism under the physiological condition remains unclear. Here, we apply a bioorthogonal itaconate probe to perform global profiling of S-itaconation in living pathogens, including S. Typhimurium, S. aureus, and P. aeruginosa. Some functional enzymes are covalently modified by itaconate, including those involved in the de novo purine biosynthesis pathway. Further biochemical studies demonstrate that itaconate suppresses this specific pathway to limit Salmonella growth by inhibiting the initiator purF to lower de novo purine biosynthesis and simultaneously targeting the guaABC cluster to block the salvage route. Our chemoproteomic study provides a global portrait of S-itaconation in multiple pathogens and offers a valuable resource for finding susceptible targets to combat drug-resistant pathogens in the future.