Listeria monocytogenes DNA Glycosylase AdlP Affects Flagellar Motility, Biofilm Formation, Virulence, and Stress Responses
ABSTRACTThe temperature-dependent alteration of flagellar motility gene expression is critical for the foodborne pathogenListeria monocytogenesto respond to a changing environment. In this study, a genetic determinant,L. monocytogenesf2365_0220(lmof2365_0220), encoding a putative protein that is structurally similar to theBacillus cereusalkyl base DNA glycosylase (AlkD), was identified. This determinant was involved in the transcriptional repression of flagellar motility genes and was namedadlP(encoding anAlkD-likeprotein [AdlP]). Deletion ofadlPactivated the expression of flagellar motility genes at 37°C and disrupted the temperature-dependent inhibition ofL. monocytogenesmotility. TheadlPnull strains demonstrated decreased survival in murine macrophage-like RAW264.7 cells and less virulence in mice. Furthermore, the deletion ofadlPsignificantly decreased biofilm formation and impaired the survival of bacteria under several stress conditions, including the presence of a DNA alkylation compound (methyl methanesulfonate), an oxidative agent (H2O2), and aminoglycoside antibiotics. Our findings strongly suggest thatadlPmay encode a bifunctional protein that transcriptionally represses the expression of flagellar motility genes and influences stress responses through its DNA glycosylase activity.IMPORTANCEWe discovered a novel protein that we namedAlkD-likeprotein (AdlP). This protein affected flagellar motility, biofilm formation, and virulence. Our data suggest that AdlP may be a bifunctional protein that represses flagellar motility genes and influences stress responses through its DNA glycosylase activity.