Salmonella secretome analysis - Discovery of novel secreted virulence factors from Salmonella enterica serovar Typhimurium by proteomic analysis of culture supernatants

Researchers identified effector proteins secreted into defined minimal medium designed to induce expression of the SPI-2 TTSS and its effectors. The secretome of the parent strain was compared to those of strains missing essential (ssaK::cat) or regulatory (ssaL) components of the SPI-2 TTSS. 20 known SPI-2 effectors were identified. To identify novel effector proteins, the secretome data was coupled with machine learning and 12 candidate proteins were selected for further characterization. Using CyaA reporter fusions, six novel type III effectors were identified and two additional proteins that were secreted into J774 macrophages independently of a TTSS were also identified.