{Reference Type}: Journal Article
{Title}: Mechanism of synergistic activation of Arp2/3 complex by cortactin and WASP-family proteins.
{Author}: Fregoso FE;Boczkowska M;Rebowski G;Carman PJ;van Eeuwen T;Dominguez R;
{Journal}: Nat Commun
{Volume}: 14
{Issue}: 1
{Year}: 2023 10 28
{Factor}: 17.694
{DOI}: 10.1038/s41467-023-42229-y
{Abstract}: Cortactin coactivates Arp2/3 complex synergistically with WASP-family nucleation-promoting factors (NPFs) and stabilizes branched networks by linking Arp2/3 complex to F-actin. It is poorly understood how cortactin performs these functions. We describe the 2.89 Å resolution cryo-EM structure of cortactin's N-terminal domain (Cort1-76) bound to Arp2/3 complex. Cortactin binds Arp2/3 complex through an inverted Acidic domain (D20-V29), which targets the same site on Arp3 as the Acidic domain of NPFs but with opposite polarity. Sequences N- and C-terminal to cortactin's Acidic domain do not increase its affinity for Arp2/3 complex but contribute toward coactivation with NPFs. Coactivation further increases with NPF dimerization and for longer cortactin constructs with stronger binding to F-actin. The results suggest that cortactin contributes to Arp2/3 complex coactivation with NPFs in two ways, by helping recruit the complex to F-actin and by stabilizing the short-pitch (active) conformation, which are both byproducts of cortactin's core function in branch stabilization.