“Omics” of Food-Borne Gastroenteritis: Global Proteomic and Mutagenic Analysis ofSalmonella entericaSerovar Enteritidis

Abstract

Salmonella Enteritidis causes food-borne gastroenteritis by the two type three secretion systems (TTSS). TTSS-1 mediates invasion through intestinal lining, and TTSS-2 facilitates phagocytic survival. The pathogens' ability to infect effectively under TTSS-1-deficient background in host's phagocytes is poorly understood. Therefore, pathobiological understanding of TTSS-1-defective nontyphoidal Salmonellosis is highly important. We performed a comparative global proteomic analysis of the isogenic TTSS-1 mutant of Salmonella Enteritidis (M1511) and its wild-type isolate P125109. Our results showed 43 proteins were differentially expressed. Functional annotation further revealed that differentially expressed proteins belong to pathogenesis, tRNA and ncRNA metabolic processes. Three proteins, tryptophan subunit alpha chain, citrate lyase subunit alpha, and hypothetical protein 3202, were selected for in vitro analysis based on their functional annotations. Deletion mutants generated for the above proteins in the M1511 strain showed reduced intracellular survival inside macrophages in vitro. In sum, this study provides mass spectrometry-based evidence for seven hypothetical proteins, which will be subject of future investigations. Our study identifies proteins influencing virulence of Salmonella in the host. The study complements and further strengthens previously published research on proteins involved in enteropathogenesis of Salmonella and extends their role in noninvasive Salmonellosis.

Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to intracellular S. Typhimurium

“…This notion is consistent with our in-vitro data showing that while STM is able to utilize ethanolamine and citrate as a sole carbon source, SPA cannot grow or grows much slower on these sources. Previous studies have shown that deficiency for citrate lyase activity (citF) leads to significant reduction in STM survival inside macrophages [77] and that an STM mutant that cannot utilize citrate is highly attenuated in the mouse [78]. Similarly, ethanolamine is released by host tissues during inflammation and a study by Thiennimitr and colleagues in mice has shown that ethanolamine metabolism provides a growth advantage to STM during intestinal colonization [75].…”

Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to Intracellular S. Typhimurium

“…This notion is consistent with our in-vitro data showing that while STM is able to utilize ethanolamine and citrate as a sole carbon source, SPA cannot grow or grows much slower on these sources. Previous studies have shown that deficiency for citrate lyase activity (citF) leads to significant reduction in STM survival inside macrophages (72) and that an STM mutant that cannot utilize citrate is highly attenuated in the mouse (73). Similarly, ethanolamine is released by host tissues during inflammation and a study by Thiennimitr and colleagues in mice has shown that ethanolamine metabolism provides a growth advantage to STM during intestinal colonization (70).…”

Acute Infectious Gastroenteritis: The Causative Agents, Omics-Based Detection of Antigens and Novel Biomarkers

“…This platform has been growing steadily and widely utilized with the supplementation of advances in both mass spectrometry and bioinformatics [ 155 ]. In detection of Salmonella Enteritidis, proteomic approaches have been used to detect isogenic Type Three Secretion System-I (TTSS-I) known as M1511 and its wild-type isolate, P125109 using a high-resolution Fourier transform mass spectrometer [ 156 ]. For Escherichia coli identification, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF MS) can also be used because it is a rapid, low cost, reliable and accurate proteomic method for E. coli identification up to the subspecies level compared with classical culture microbiological techniques [ 157 , 158 ].…”