Dual perspective proteomics infectome profiling discoversSalmonellatype III secretion system effector functions in macrophages

Abstract

Intracellular bacterial pathogens have evolved sophisticated infection strategies, including the release and secretion of virulence factors to interfere with host cell functions and to perturb immune responses. For Salmonella enterica serovar Typhimurium (S. Typhimurium), the type III secretion systems encoded on Salmonella pathogenicity islands (SPI) 1 and 2 mediates invasion of the bacterium into innate immune cells and regulates bacterial replication and survival within the hostile environment of the host, respectively. Here, we explore the temporal and strain-specific dual perspective response of both the host and pathogen during cellular infection via quantitative proteomics. We report time- and pathogenicity island-specific expression and secretion of infection-associated proteins (i.e., SL1344_1263, SL1344_3112, SL1344_1563, and YnhG) and regulated immune response proteins in macrophage, including Cd86, Cd40, Casp4, C3, IL-1?, and Cd69). Through intracellular macrophage and in vivo murine models of infection, we reveal a role in virulence for three of the bacterial proteins (SL1344_1263, SL1344_1563, and YnhG), defining their importance as novel T3SS effectors. We characterize the temporal intra- and extracellular production of the effectors and identify their interaction networks in host cells, representing inhibitory and stimulatory pathways mounted by invading bacterial pathogens.

Recent Advancements in Tracking Bacterial Effector Protein Translocation

“…Strikingly, some pathogens secrete tens or even hundreds of effectors (e.g., Legionella pneumophila encodes over 300 T4Es, with 3027 predicted protein-encoding genes in total), while others only secrete a few effectors (e.g., Pseudomonas aeruginosa encodes 4 T3Es) [18,19]. In case of Salmonella, two T3SSs encoded on two different pathogenicity islands, i.e., SPI-1 and SPI-2, facilitate the delivery of around 50 T3Es into infected cells [20,21]. While SPI-1 encoded T3Es direct the early biogenesis of the Salmonella-containing vacuole (SCV), SPI-2 T3Es are responsible for the subsequent SCV maturation, intracellular bacterial survival, and direction of the systemic phase of infection [22].…”

Dual proteomic signature of immune cells andYersinia pestisupon blood infection

“…However, complex samples are still challenging to tackle. Culture-independent bacterial identification by proteo-typing in complex matrices such as blood or urine using tandem mass-spectrometry for clinical diagnosis is in its infancy (Roux-Dalvai et al 2019;Kondori et al 2021), and very few dual-proteomics research studies investigating complex host-pathogen interactions have been published (Geddes-McAlister et al 2021;Ball et al 2020;Willems et al 2021;Leseigneur et al 2022;Masson et al 2021). Additionally, research on highly virulent microorganisms is restricted by regulatory requirements for safety purposes.…”