Fig. 3: Models comparing interactions of Arp3 with daughter filament subunit D1 in branch junctions with ADP-BeFx or ADP.
a Ribbon diagrams of Arp3 and D1 from the branch junction with BeFx nucleotide. A box highlights part of the interface between daughter subunit D1 and Arp3 shown in more detail in (b) and (c). b Ribbon diagrams with stick figures of residues 44-49 of the D-loop of actin subunit D1 in the ADP-BeFx state. The interaction of the D-loop with Arp3 is stabilized by hydrophobic interactions including actin D1 residues M44 and M47 with Arp3 and multiple hydrogen bonds: Arp3 R177 with the backbone oxygen of actin M47; and the side chain of actin Q49 with the backbones of both its own G48 and Arp3 G199. c In ADP state the outer domain of Arp3 twists by 2°, so the hydrogen bonding interactions are further apart, thus weakening the Arp3-D1 interface.
