The cell wall of Listeria monocytogenes and its role in pathogenicity

Abstract

Listeria monocytogenes contains a cell wall formed by a multilayered crosslinked peptidoglycan decorated with teichoic and lipoteichoic acids. Like in all eubacteria, the cell wall of L. monocytogenes plays a critical role in its physiology since it ensures integrity of the cell while maintaining a high internal osmotic pressure. In addition, it also endows the cell with a specific cell shape and provides protection against mechanical stress. As in other noncapsulated grampositive bacteria, the cell wall of L. monocytogenes is the outermost structure of the cell and acts as a scaffold in which different proteins anchor. L. monocytogenes is a highly successful pathogen that invades eukaryotic host cells, crosses several natural barriers of the host and survives to extreme environments, and its cell wall must necessarily contain molecules making possible the colonization of these niches. The role in pathogenesis of some of these surface molecules is just starting to be deciphered. Likewise, the genome sequences now known for a few L. monocytogenes strains reveal that this pathogen has a large number of genes encoding proteins with domains mediating interactions with cell-wall polymers. Some of these cell-wall-associated proteins are currently subjected to intense investigation. Recent studies have also revisited the structure of the peptidoglycan of L. monocytogenes and unravelled new modifications in its structure that may be important for pathogenicity.