OpuCA mediates oxidative stress tolerance and host infection of Listeria monocytogenes

Abstract:

[Objective] Listeria monocytogenes, the important foodborne pathogen, uses opuCA gene to defend against osmotic stress. In this study, we explored the roles of opuCA gene in growth, pathopoiesis, oxidative stress resistance, and osmotic stress resistance of L.monocytogenes, hoping to lay a basis for clarifying the mechanism of OpuCA-mediated bacterial adaptation and infection. [Methods] We constructed the opuCA deletion mutant (ΔopuCA) and complementary mutant (CΔopuCA) and then compared the growth, oxidative stress tolerance, osmotic stress tolerance, and cellular adhesion and invasion of the wild strain and the mutants by molecular biology technology, infection biology technology, and laser scanning confocal microscopy. [Results] opuCA deletion had no influence on bacterial growth but decreased the osmotic stress tolerance. Additionally, ΔopuCA showed low tolerance to Cu²⁺and Cd²⁺compared with the wild strain, but the tolerance to thiol-specific oxidant diamide demonstrated no obvious variation. Furthermore, loss of opuCA significantly reduced bacterial adhesion and invasion to Caco-2 cells, and actin aggregation, thereby influencing the intercellular migration of bacteria. [Conclusion] opuCA plays a critical role in bacterial osmotic stress tolerance, oxidative stress resistance, and intracellular infection. This study expands our understanding of the OpuCA-mediated in vitro adaption and pathopoiesis of L.monocytogenes, which lays a basis for the prevention and control of the foodborne diseases caused by L.monocytogenes.