Autoinhibition and cooperative activation mechanisms of cytoplasmic dynein

Abstract

Cytoplasmic dynein is a two-headed microtubule-based motor responsible for diverse intracellular movements, including minus-end-directed transport of organelles. The motility of cargo transporters is regulated according to the presence or absence of cargo; however, it remains unclear how cytoplasmic dynein achieves such regulation. Here, using a recombinant and native dynein complex in vitro, we show that lone, single dynein molecules are in an autoinhibited state, in which the two motor heads are stacked together. In this state, dynein moves diffusively along a microtubule with only a small bias towards the minus end of the microtubule. When the two heads were physically separated by a rigid rod, the movement of dynein molecules became directed and processive. Furthermore, assembly of multiple dynein molecules on a single cargo enabled them to move unidirectionally and generate force cooperatively. We thus propose a mechanism of autonomous on-off switching of cargo transport, in which single dynein molecules in the cell are autoinhibited through intramolecular head-head stacking and become active when they assemble as a team on a cargo.

Two classes of short intraflagellar transport train with different 3D structures are present in Chlamydomonas flagella

“…These considerations suggest that the backbone structure of narrow short trains might be formed by stacked particles that are linked through motors to the doublet. We do not have any evidence about which motor is engaged on the doublet in these trains, but note that the organization of the 16-nm-repeating structural units occurring on one side of the train (lobe c) is compatible with that of inactive dynein molecules, whose ultrastructure has been recently described (Torisawa et al, 2014). If our hypothesis is correct, it would imply that narrow short trains move in an anterograde fashion.…”

Combinatorial regulation of the balance between dynein microtubule end accumulation and initiation of directed motility

“…Lis1 binds the AAA+ ring of the dynein motor domain (Tai et al , 2002; Huang et al , 2012) and the p50 subunit of dynactin (Tai et al , 2002), whereas BicD2 interacts with the dynein tail and the Arp1 filament of dynactin (Chowdhury et al , 2015; Urnavicius et al , 2015). Interestingly, Lis1 has been shown to bind to a compact dynein conformation with docked motor domains (also known as the phi particle) (Toba et al , 2015) that has been proposed to correspond to an autoinhibited state of the dynein motor (Torisawa et al , 2014). In contrast, in the DDB particle the motor domains of dynein show a splayed configuration, possibly corresponding to its processive conformation (Urnavicius et al , 2015; Carter et al , 2016).…”

A mathematical understanding of how cytoplasmic dynein walks on microtubules

“…While these experimental studies enable detailed understanding of dynein's structure [2,4,7,18–21,35] and transport mechanism [3,34,36,37,42,47,48,52]; to our knowledge, few models have been developed to describe such observations [53–55]. Our results bridge this gap, by presenting a robust integrative mechanical and stochastic model describing the stepping behaviour of cytoplasmic dynein.…”

“…Those that focus on the single molecule motility properties of dynein [3,21,36,37] and those that focus on the mechanical structural dynamics of dynein [2,20,21,35,38]. Furthermore, experimental data both in vivo [39–41] and in vitro [2,4,42] are performed and obtained on different species (e.g. yeast [3,35], Dictyostelium discoideum [2,4,7,20,23], human [38,42], Saccharomyces cerevisiae [21,36,37], etc.).…”

“…Furthermore, experimental data both in vivo [39–41] and in vitro [2,4,42] are performed and obtained on different species (e.g. yeast [3,35], Dictyostelium discoideum [2,4,7,20,23], human [38,42], Saccharomyces cerevisiae [21,36,37], etc.). Moreover, studies are carried out either in one-dimension [37] or two-dimensions [4,36,37].…”