Structural insights into the assembly of a monomeric class V myosin

Abstract

Motor proteins are a vital contributor to life, where they manifest themselves in the directed movement of organisms, in cell division, and in the transport of organelles, proteins, and nucleic acids. The “Big Three” superfamilies of linear motor proteins consist of myosin, kinesin, and dynein, which move along actin or microtubules. Over the past 60 y, since the discovery of the sliding filament model for muscle contraction and the identification of myosin as the active component, considerable effort has been devoted to understanding the molecular properties of the motor domains that generate directed movement. In contrast, considerably less is known about the structural interactions of these motors with their partners, which is ironic because motors only exist to move or apply force to something! Not surprisingly, this is a rich area for investigation that is now yielding an understanding of not only the structural themes but also the regulation of motors by their cargoes. An example of this is seen in PNAS, where Shi et al. (1) reveal how the budding yeast myosin Myo4p, a class V myosin, interacts with its partners She3p and She2p to facilitate transport of mRNA. The report by Shi et al. provides structural insight into how cargo binding efficiently regulates this myosin through oligomerization rather than through a disruption of a direct head-tail inhibitory interaction as often seen in many myosins (2) and members of the kinesin superfamily (3, 4).