INTERACTION OF HUMAN ARP2 3 COMPLEX AND THE LISTERIA-MONOCYTOGENES ACTA PROTEIN IN ACTIN FILAMENT NUCLEATION/

Actin filament assembly at the cell surface of the pathogenic bacteriu m Listeria monocytogenes requires the bacterial ActA surface protein a nd the host cell Arp2/3 complex. Purified Arp2/3 complex accelerated t he nucleation of actin polymerization in vitro, but pure ActA had no e ffect. However, when combined, the Arp2/3 complex and ActA synergistic ally stimulated the nucleation of actin filaments. This mechanism of a ctivating the host Arp2/3 complex at the L. monocytogenes surface may be similar to the strategy used by cells to control Arp2/3 complex act ivity and hence the spatial and temporal distribution of actin polymer ization.