The glucoside transporter Lmo0738 contributes to virulence of Listeria monocytogenes

Abstract:

[Objective] To investigate the biological role played by the glucoside transporter Lmo0738 in the virulence of Listeria monocytogenes. [Methods] The lmo0738-deleted mutant (Δlmo0738) and complementation mutant (CΔlmo0738) were constructed by homologous recombination. The growth, hemolytic activity, cellular adhesion and invasion, and intracellular migration of the wild type strain and the mutants were assessed by the growth curves, sheep red blood cell hemolysis assay, infection of human epithelial cells (Caco-2), and infection of mouse fibroblastic cells (L929), respectively. Additionally, the mRNA and protein levels of the virulence factor listeriolysin O (LLO) were determined by real-time quantitative reverse transcription PCR (RT-qPCR) and Western blotting, respectively. [Results] The L. monocytogenes strain with the deletion of lmo0738 demonstrated weakened growth and diminished hemolytic activity. Notably, Δlmo0738 exhibited significantly reduced cell adhesion, invasion, and intracellular migration compared with the wild type strain. In addition, the mRNA and protein levels of LLO were significantly down-regulated in Δlmo0738. [Conclusion] This study provides the evidence that the absence of lmo0738 attenuates the virulence of L. monocytogenes, laying a crucial foundation to illustrate the mechanism of the phosphotransferase system (PTS) in regulating the sugar catabolism and the infection mechanism of major food-borne pathogens including L. monocytogenes.