Small-molecule inhibitors of the AAA+ ATPase motor cytoplasmic dynein

Abstract

A family of small molecules called ‘ciliobrevins’ are described that can rapidly and reversibly modulate the AAA+ ATPase motor dynein, which transports cargo molecules along microtubule tracks. Enzymes of the AAA+ ATPase family convert chemical potential energy into the mechanical forces required for cellular processes, such as cargo transport and cytoskeleton disassembly. Here, Firestone et al. describe a class of small molecules called ciliobrevins. These molecules can rapidly and reversibly modulate the AAA+ ATPase motor, dynein, which transports cargo molecules along microtubule tracks. The ciliobrevins will be useful as molecular probes of dynein function. The conversion of chemical energy into mechanical force by AAA+ (ATPases associated with diverse cellular activities) ATPases is integral to cellular processes, including DNA replication, protein unfolding, cargo transport and membrane fusion1. The AAA+ ATPase motor cytoplasmic dynein regulates ciliary trafficking2, mitotic spindle formation3 and organelle transport4, and dissecting its precise functions has been challenging because of its rapid timescale of action and the lack of cell-permeable, chemical modulators. Here we describe the discovery of ciliobrevins, the first specific small-molecule antagonists of cytoplasmic dynein. Ciliobrevins perturb protein trafficking within the primary cilium, leading to their malformation and Hedgehog signalling blockade. Ciliobrevins also prevent spindle pole focusing, kinetochore–microtubule attachment, melanosome aggregation and peroxisome motility in cultured cells. We further demonstrate the ability of ciliobrevins to block dynein-dependent microtubule gliding and ATPase activity in vitro. Ciliobrevins therefore will be useful reagents for studying cellular processes that require this microtubule motor and may guide the development of additional AAA+ ATPase superfamily inhibitors.