AgrD-dependent quorum sensing affects biofilm formation, invasion, virulence and global gene expression profiles in Listeria monocytogenes

Abstract

The Listeria monocytogenes Agr peptide-sensing system has been analysed by creating a deletion mutant in agrD, the structural gene for the putative quorum-sensing peptide. The ΔagrD mutant displayed significantly reduced biofilm formation, a defect which could be restored by genetic or physical complementation. A reduced invasion of Caco-2 intestinal epithelial cells was observed for the ΔagrD mutant while phagocytosis by THP-1 macrophages was unaffected. Additionally, the level of internalin A (InlA) in the cell wall was decreased in the ΔagrD mutant. Expression profiling of virulence genes (hlyA, actA, plcA, prfA and inlA) identified a finely tuned regulation which resulted in an impaired ..