Deletion of the oligopeptide transporter Lmo2193 decreases the virulence of Listeria monocytogenes.

Background: is a gram-positive bacterium that causes listeriosis mainly in immunocompromised hosts. It can also cause foodborne outbreaks and has the ability to adapt to various environments. Peptide uptake in gram-positive bacteria is enabled by oligopeptide permeases (Opp) in a process that depends on ATP hydrolysis by OppD and F. Previously a putative protein was predicted to be OppD, but little is known about the role of OppD in major processes of , such as growth, virulence, and biofilm formation.

Objectives: To determine whether the virulence traits of are related to OppD.

Methods: In this study, lmo2193 gene deletion and complementation strains of were generated and compared with a wild-type strain for the following: adhesiveness, invasion ability, intracellular survival, proliferation, 50% lethal dose (LD) to mice, and the amount bacteria in the mouse liver, spleen, and brain.

Results: The results showed that virulence of the deletion strain was 1.34 and 0.5 orders of magnitude higher than that of the wild-type and complementation strains, respectively. The function of Lmo2193 was predicted and verified as OppD from the ATPase superfamily. Deletion of affected the normal growth of , reduced its virulence in cells and mice, and affected its ability to form biofilms.

Conclusions: Deletion of the oligopeptide transporter Lmo2193 decreases the virulence of . These effects may be related to OppD's function, which provides a new perspective on the regulation of oligopeptide transporters in .