Pivotal role of VASP in Arp2/3 complex–mediated actin nucleation, actin branch-formation, and Listeria monocytogenes motility

J Skoble, V Auerbuch, ED Goley, MD Welch… - The Journal of cell …, 2001 - rupress.org
J Skoble, V Auerbuch, ED Goley, MD Welch, DA Portnoy
The Journal of cell biology, 2001rupress.org
The Listeria monocytogenes ActA protein mediates actin-based motility by recruiting and
stimulating the Arp2/3 complex. In vitro, the actin monomer-binding region of ActA is critical
for stimulating Arp2/3-dependent actin nucleation; however, this region is dispensable for
actin-based motility in cells. Here, we provide genetic and biochemical evidence that
vasodilator-stimulated phosphoprotein (VASP) recruitment by ActA can bypass defects in
actin monomer-binding. Furthermore, purified VASP enhances the actin-nucleating activity …
The Listeria monocytogenes ActA protein mediates actin-based motility by recruiting and stimulating the Arp2/3 complex. In vitro, the actin monomer-binding region of ActA is critical for stimulating Arp2/3-dependent actin nucleation; however, this region is dispensable for actin-based motility in cells. Here, we provide genetic and biochemical evidence that vasodilator-stimulated phosphoprotein (VASP) recruitment by ActA can bypass defects in actin monomer-binding. Furthermore, purified VASP enhances the actin-nucleating activity of wild-type ActA and the Arp2/3 complex while also reducing the frequency of actin branch formation. These data suggest that ActA stimulates the Arp2/3 complex by both VASP-dependent and -independent mechanisms that generate distinct populations of actin filaments in the comet tails of L. monocytogenes. The ability of VASP to contribute to actin filament nucleation and to regulate actin filament architecture highlights the central role of VASP in actin-based motility.
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