Proteomic discovery of host kinase signaling in bacterial infections.

Protein phosphorylation catalyzed by protein kinases acts as a reversible molecular switch in signal transduction, providing a mechanism for the control of protein function in cellular processes. During microbial infection, cellular signaling essentially contributes to immune control to restrict the dissemination of invading pathogens within the host organism. However, pathogenic microbes compete for the control of host signaling to create a beneficial environment for successful invasion and infection. Although efforts to achieve a better understanding of the host-pathogen interaction and its molecular consequences have been made, there is urgent need for a comprehensive characterization of infection-related host signaling processes. System-wide and hypothesis-free analysis of phosphorylation-mediated host signaling during host-microbe interactions by mass spectrometry (MS)-based methods is not only promising in view of a greater understanding of the pathogenesis of the infection but also may result in the identification of novel host targets for preventive or therapeutic intervention. Here, we review state-of-the-art MS-based techniques for the system-wide identification and quantitation of protein phosphorylation and compare them to array-based phosphoprotein analyses. We also provide an overview of how phosphoproteomics and kinomics have contributed to our understanding of protein kinase-driven phosphorylation networks that operate during host-microbe interactions.