Cell-selective proteomic analysis of host-microbe interactions using Bio-orthogonal Noncanonical Amino Acid Tagging (BONCAT)

Abstract

While proteomic studies of microbes in culture have provided many important biol. insights, there is a need for more global analyses of their behavior during interactions within mammalian hosts. However, abundant host tissues often dominate and obstruct system-wide profiling of proteins expressed by microbes in mouse models. We have adapted bio-orthogonal non-canonical amino add tagging (BONCAT), a chemoproteomic tool for detecting newly-synthesized proteins in complex biol. systems, to cell-selectively label and identify microbial proteins while infecting or colonizing a live mouse. Diverse species of microbes have been labeled using this technique, Including methicillin-resistant Staphylococcus aureus (MRSA), and the human gut commensal, Bacteroides fragilis. When coupled to click. chem., this cell-selective technique can be used to visualize proteomes in space and time using fluorescence microscopy, or to enrich and identify proteins using mass spectrometry. In addn. to confirming well-established virulence factors in MRSA, we found a previously unidentified factor, and the top BONCAT hit, to play a crit. role in skin infection models. Furthermore, we are exploring combining this method with passive CLARITY techniques to visualize microbial population dynamics within mice. Our work demonstrates the power of unbiased chemoproteomic labeling in vivo. A08.