identification of the endogenous insoluble host targets of the Salmonella effectors SSeK3

Strains of Salmonella utilise two distinct type three secretion systems to deliver effector proteins directly into host cells. The Salmonella effector SseK3 is a arginine glycosyltransferase that modify mammalian proteins with N-acetyl glucosamine (GlcNAc). Here, we used Arg-GlcNAc glycopeptide immunoprecipitation and mass spectrometry appraoch to identify host proteins GlcNAcylated by endogenous levels of SseK3 during Salmonella infection. Focusing on the insoluble proteome we demostrate multiple typically insoluble proteins are targetted by SseK3 during infections. Surpisingly unlike SseK1 and the EPEC homologue NleB1 which target death domain contain proteins SseK3 appears to modify a number of proteins lacking death domains. These results demostrate that under endogenous infection non-death domain containing proteins can be modified by Salmonella.