Objective:To identify new host substrate of SseK3 and study its biological function.Methods:A yeast two hybrid system (Y2H) was used to identify the potential binding proteins of SseK3 from the Hela cDNA library; the arginine N-acetylglucosamine (Arg-GlcNAc) modification of the substrate protein by SseK3 was detected by co-expression in 293T cells and in vitro activity test; the modification sites of the substrate protein by SseK3 were detected by point mutation; the effect of Arg-GlcNAc modification of the substrate protein on its interaction protein binding ability was detected by immunoprecipitation test. Results:Results of Y2H and gene sequencing showed that Snapin was a new substrate of SseK3. Snapin could be Arg-GlcNAc-modified by SseK3 in vivo and in vitro; the modification sites of Snapin were arginine 119 and arginine 120; Arg-GlcNAc-modified Snapin inhibited its binding with SNAP25. Conclusions:Snapin, a new host substrate protein of SseK3, was successfully screened in this study. The Arg-GlcNAc modification of Snapin by SseK3 was studied, and the effect of this modification on Snapin function was preliminarily studied, which provided theoretical basis for further understanding the function of Arg-GlcNAc modification of bacteria and the mechanism of action in the process of pathogen infection.