Kinesin-1, -2, and -3 motors use family-specific mechanochemical strategies to effectively compete with dynein during bidirectional transport

Abstract

Bidirectional cargo transport in neurons requires competing activity of motors from the kinesin-1, -2 and -3 superfamilies against cytoplasmic dynein-1. Previous studies demonstrated that when kinesin-1 attached to dynein-dynactin-BicD2 (DDB) complex, the tethered motors move slowly with a slight plus-end bias, suggesting kinesin-1 overpowers DDB but DDB generates a substantial hindering load. Compared to kinesin-1, motors from the kinesin-2 and -3 families display a higher sensitivity to load in single-molecule assays and are thus predicted to be overpowered by dynein complexes in cargo transport. To test this prediction, we used a DNA scaffold to pair DDB with members of the kinesin-1, -2 and -3 families to recreate bidirectional transport in vitro, and tracked the motor pairs using two-channel TIRF microscopy. Unexpectedly, we find that when both kinesin and dynein are engaged and stepping on the microtubule, kinesin-1, -2, and -3 motors are able to effectively withstand hindering loads generated by DDB. Stochastic stepping simulations reveal that kinesin-2 and -3 motors compensate for their faster detachment rates under load with faster reattachment kinetics. The similar performance between the three kinesin transport families highlights how motor kinetics play critical roles in balancing forces between kinesin and dynein, and emphasizes the importance of motor regulation by cargo adaptors, regulatory proteins, and the microtubule track for tuning the speed and directionality of cargo transport in cells.

KIF1A is kinetically tuned to be a superengaging motor under hindering loads

“…These features confer a distinct advantage during intracellular transport because they increase the probability that when a motor detaches from the microtubule it will rapidly reengage to continue transport. A recent study that tethered kinesin-1 and kinesin-3 motors to dynein-dynactin-BicD2 complexes found that KIF1A could compete against dynein nearly as effectively as kinesin-1, despite their different load-dependent off-rates ( 59 ). Importantly, a computational model that incorporated slow (5 s −1 ) ( 58 , 60 ) reattachment rates for KIF1A and kinesin-1 was unable to recapitulate the data, but if the reengagement rates were set to 990 s −1 for KIF1A and to 100 s −1 for kinesin-1 from Fig.…”

Microtubule acetylation dyshomeostasis in Parkinson’s disease

“…A single dynein-dynactin-BICD2 (DDB) complex has the potential to successfully resist one kinesin module [ 56 ]. When both kinesin and dynein are stepping simultaneously on the MTs and are engaged in competing activity, the kinesin-1, -2 and -3 motors are observed to overpower the hindering forces exerted by the DDB complex via innate mechanochemical strategies and bias the overall cargo movement toward the plus-end [ 57 ]. The dynein light chain TCTEX1 has been reported to associate with the mitochondria via interactions with voltage-dependent anion selective channel 1 in the outer mitochondrial membrane [ 58 ].…”

Optogenetic control of kinesins -1, -2, -3 and dynein reveals their specific roles in vesicular transport

“…We extended the mathematical model developed by Müller et al (40) to simulate the motility of a cargo driven by any number of different types of motors (see Methods). We estimated motor parameters such as binding rate, detachment rate, detachment force, stall force, forward and backward velocities based on previous single-molecule experiments and published models, following closely the analysis in (41) (see methods). To simulate different vesicle populations, we used estimates of the number of motors on each of these cargoes from previous single-molecule fluorescence and quantitative photobleaching experiments (42).…”