Regulatory role of Listeria monocytogenes glutathione synthetase in bacterial motility and flagellar production

Abstract:

[Objective] The foodborne pathogen Listeria monocytogenes is well-adapted outside of the environmental conditions and inside of the host niche by delicately controlling flagellar production. We here aimed to explore the regulatory roles of L. monocytogenes glutathione synthetase (encoded by gshF) in bacterial motility and flagella production.[Methods] The gene knock-out mutant and complemented strains (ΔgshF and CΔgshF) were constructed and then subjected to in vitro bacterial growth and motility assays compared with the wild-type strain EGD-e. In addition, transcriptional changes of the flagella-associated genes were determined for the wild-type and gshF mutant strains using the Real-time Quantitative Reverse Transcription PCR (qRT-PCR) method.[Results] The data showed that in vitro growth ability was not significantly affected by deletion of gshF while the swarming ability of ΔgshF was markedly impaired. More importantly, the transcriptional levels of the flagellar-associated factors GmaR, a protein thermometer that controls temperature-dependent transcription of flagellar genes, and FlaA, encoding flagellin, were most significantly down-regulated at 30℃ in the absence of gshF.[Conclusion] We in this study showed that the glutathione synthetase of L. monocytogenes plays a vital role in controlling transcription of flagellar genes and contributes to bacterial swarming motility and flagellar production. These data would be helpful to better understand the regulatory mechanisms employed by this intracellular pathogen to favor environmental adaption and host infection.