Abp1 regulation of branched actin networks

Branched actin filament networks formed by the Arp2/3 complex play an essential role in force production in eukaryotic cells.  Branched networks are not static components of the cytoskeleton.  Instead the times and locations of network assembly  and disassembly are tightly controlled by regulatory proteins.  Ph.D. student Siyang Guo used single-molecule fluorescence methods to show how the Abp1 protein positively regulates branched actin networks.  Remarkably, Apb1 functions by two distinct mechanisms.  The protein stimulates the formation of networks by stabilizing the binding of Arp2/3 complex to the sides of actin filaments, a precursor to branch formation.  However after branches form bound Abp1 works differently: it protects the network from GMF, the “pruning shears” protein that chops off branches during network disassembly.  Taken as a whole, the study gives deeper insight into the multiple layers of regulation that control cytoskeleton pattern formation and dynamics.  This project is part of a long-term collaboration on cytoskeletal regulation with Bruce Goode’s lab.

Abp1 promotes Arp2/3 complex-dependent actin nucleation and stabilizes branch junctions by antagonizing GMF
Siyang Guo, Olga S. Sokolova, Johnson Chung, Shae Padrick, Jeff Gelles, Bruce L. Goode
Nature Communications (2018) 9:2895.