Technologies for Proteome-Wide Discovery of Extracellular Host-Pathogen Interactions

Martinez-Martin, Nadia

Another MS-based approach that holds great promise for host-pathogen ePPI detection is the recently developed TRICEPS [33] . TRICEPS is a chemoproteomic reagent that consists of three moieties, one that binds the ligand of interest through its amino groups, a second one that binds glycosylated receptors on the cell surface, and a biotin tag for purifying the receptor peptides for subsequent identification by MS. Notably, in the initial description of the method, TRICEPS was successfully applied to the identification of receptors for extracellular ligands of diverse nature, such as secreted glycoproteins, small peptide ligands for G proteincoupled receptors, and therapeutic antibodies. Importantly, this approach has also been utilized to study cell surface molecules targeted by vaccinia virus (VACV). Interestingly, the analysis of VACV binding to HeLa cells revealed seven candidate binding partners, including the previously identified receptors AXL, chondroitin sulfate proteoglycan 4, and laminin binding protein dystroglycan 1. Further, downregulation of five out of the seven candidates using short interfering RNA reduced VACV infection by 40-60%, supporting the functionality of the interactions identified, at least in vitro [33] . Although this technology is still developing and no studies on other pathogens have been published yet, future TRICEPS-based studies promise relevant insights into pathogen interaction with distinct components of the cell surface.