Latrunculin alters the actin-monomer subunit interface to prevent polymerization

Abstract

Latrunculin-A is a drug that is capable of rapidly, reversibly and specifically disrupting the actin cytoskeleton. The efficacy of its action has made it a compound of choice in many cell-biology laboratories, supplanting the classic actin-depolymerizing drug cytochalasin-D. One reason for this is that the mode of action of latrunculin seems to be less complex than that of cytochalasin. Whereas the latter affects the kinetics of actin-filament polymerization at both the barbed and pointed ends, latrunculin-A seems to associate only with actin monomers, thereby preventing them from repolymerizing into filaments. The association of latrunculin with monomeric, rather than filamentous, actin gave us the opportunity to further our understanding of this interaction by detailed structural analysis of actin monomers using crystallographic techniques. Here we show the first high-resolution structure of an actin-disrupting drug in association with actin and discuss how its interactions with actin, and the conformational changes that its binding causes, may explain its mode of action within the cell.