HOST-PATHOGEN INTERACTIONS DURING ENTRY AND ACTIN-BASED MOVEMENT OF LISTERIA-MONOCYTOGENES

Listeria monocytogenes is a pathogenic bacterium that induces its own uptake into mammalian cells, and spreads from one cell to another by a n actin-based motility process, Entry into host cells involves the bac terial surface proteins InlA (internalin) and InlB. The receptor for I nlA is the cell adhesion molecule E-cadherin. InlB-mediated entry requ ires activation of the host protein phosphoinositide (PI) S-kinase, pr obably in response to engagement of a receptor. Actin-based movement o f L. monocytogenes is mediated by the bacterial surface protein ActA. The N-terminal region of this protein is necessary and sufficient for polymerization of host cell actin. Other host proteins involved in bac terial motility include profilin, Vasodilator-Stimulated Phosphoprotei n (VASP), the Arp2/Arp3 complex, and cofilin. Studies of entry and int racellular movement of L. monocytogenes could lead to a better underst anding of receptor-ligand signaling and dynamics of actin polymerizati on in mammalian cells.