A kinesin-1 variant reveals motor-induced microtubule damage in cells

Abstract

Kinesins drive the transport of cellular cargoes as they walk along microtubule tracks, however, recent work has suggested that the physical act of kinesins walking along microtubules can stress the microtubule lattice. Here, we describe a kinesin-1 KIF5C mutant with an increased ability to generate defects in the microtubule lattice as compared to the wild-type motor. Expression of the mutant motor in cultured cells resulted in microtubule breakage and fragmentation, suggesting that kinesin-1 variants with increased damage activity would have been selected against during evolution. The increased ability to damage microtubules is not due to the altered motility properties of the mutant motor as expression of the kinesin-3 motor KIF1A, which has similar single-motor motility properties, also caused increased microtubule pausing, bending, and buckling but not breakage. In cells, motor-induced microtubule breakage could not be prevented by increased α-tubulin K40 acetylation, a post-translational modification known to increase microtubule flexibility. In vitro, lattice damage induced by wild-type KIF5C was repaired by soluble tubulin and resulted in increased rescues and microtubule growth whereas lattice damage induced by the KIF5C mutant resulted in larger repair sites that made the microtubule vulnerable to breakage and fragmentation when under mechanical stress. These results demonstrate that kinesin-1 motility causes defects in and damage to the microtubule lattice in cells. While cells have the capacity to repair lattice damage, conditions that exceed this capacity result in microtubule breakage and fragmentation and may contribute to human disease.

Fabrication of High Aspect Ratio Gold Nanowires within the Microtubule Lumen

“…In such a scenario, the distribution of entry points along the microtubule and the subsequent diffusion range of the gold precursor within the lumen will mainly determine the maximal number and length of the AuNWs. Hence, inducing additional lattice defects in the mold microtubule, for example, by exposing them to mechanical stress, − might increase overall nanowire length and frequency.…”

Running Kinesin-1 shapes the microtubule acetylation gradient

“…Shaft damage can regulate microtubule length and lifetime 36,37,46,49 . In addition, our data show that damage sites can also regulate microtubule posttranslational modifications (Fig.…”

“…Damage sites along the microtubule can result from different phenomena: i) imperfect polymerization, ii) occur spontaneously, iii) mechanical forces, or iv) activity of proteins including severing enzymes. Molecular motors do not only use microtubules to transport their cargo, but also generate stress within the microtubule which can damage their underlying microtubule tracks [33][34][35][36][37][38][39] .…”

The force required to remove tubulin from the microtubule lattice

“…In addition to severing enzymes, molecular motors such as kinesins and dynein can also remove tubulin subunits from the shafts of microtubules as they walk [26][27][28] . This removal of tubulin dimers from the internal lattice is distinct from the well-known activities of motors removing tubulin from microtubule ends 29 .…”