Characterizing in-vivo Virus-Host Interactions Using Chemical Cross-linking and Mass Spectrometry

Viral entry into host cells is mediated by viral surface proteins interacting with specific cell surface receptors. While the viral surface protein is often known, the host cell target is generally unknown. A method to identify cellular proteins involved in viral entry would be of great advantage. Our goal is to show the effectiveness of chemical cross-linking mass spectrometry (CXMS) and proteomics approaches to identify virus-host interactions. CXMS is a high-throughput and sensitive technique that covalently stabilizes protein-protein interactions and allows adjacent amino acids to be identified. It is known that bacteriophage lambda infects Escherichia coli using the maltose receptor (maltoporin) of the host cell. Here bacteriophage lambda is leveraged as a model system to identify the interaction of maltoporin of Escherichia coli and J protein of the phage tail. Phage lambda was pre-incubated with Escherichia coli cells and 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide, a zero length crosslinker, was then added to the sample. The cross-linked proteins were subsequently digested with trypsin and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using a high resolution Orbitrap mass spectrometer. The obtained MS spectra were analyzed by the CXMS informatics pipeline xComb to identify chemical crosslinks between the cellular maltoporin and the phage J protein. We anticipate that the CXMS approach will confirm the virus-host interaction in vivo. The identification of proteins involved in virus-host interaction can lead to the production of new drugs and therapies which can block virus-host interactions and ultimately viral infection.