Ubiquitination serves as a critical signal in the host immune response to infection. Many pathogens have evolved strategies to exploit the ubiquitin (Ub) system to promote their own survival through a complex interplay between host defense machinery and bacterial virulence factors. Here we report dynamic changes in the global ubiquitinome of host epithelial cells and invading pathogen in response to Salmonella Typhimurium infection. The most significant alterations in the host ubiquitinome concern components of the actin cytoskeleton, NF-κB and autophagy pathways, and the Ub and RHO GTPase systems. Specifically, infection-induced ubiquitination promotes CDC42 activity and linear ubiquitin chain formation, both being required for NF-κB activation. Conversely, the bacterial ubiquitinome exhibited extensive ubiquitination of various effectors and several outer membrane proteins. Moreover, we reveal that bacterial Ub-modifying enzymes modulate a unique subset of host targets, affecting different stages of Salmonella infection.
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