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

Martinez-Martin, Nadia

More recently, Yu and colleagues applied NAPPA technology in combination with the HaloTag-Halo ligand detection system to elucidate the interaction network of two effector proteins (SidM and LidA) encoded by Legionella pneumophila, a highly pathogenic bacteria that is the causative agent of Legionnaire's pneumonia [94] . Similarly to many 8 Journal of Immunology Research pathogen proteins, these virulence factors lack significant homology to host molecules therefore complicating the assessment of their host targets and biological functions. In this work, the bacterial proteins of interest were tagged with a HaloTag, a modified haloalkane dehalogenase that covalently binds to synthetic Halo-ligands (haloalkanes) that can be fluorescently labeled, thus allowing more robust detection of bait protein binding to interactors present on the array. In this study, more than 10,000 human proteins were expressed on the NAPPA array using different IVTT techniques, leading to identification of 20 and 18 binding partners for the LidA and SidM effectors, respectively, most of them experimentally verified by pull-down [94] . Although this study focused on identification of intracellular PPI, the applicability of the NAPPA-HaloTag technology for ePPI determination should be explored in the future. Moreover, bait multimerization strategies should be implemented in order to make this approach more suitable for detection of transient PPIs.