Differential trafficking of Kif5c on tyrosinated and detyrosinated microtubules in live cells

Abstract

Kinesin-1 is a molecular transporter that trafficks along microtubules. There is some evidence that kinesin-1 targets specific cellular sites, but it is unclear how this spatial regulation is achieved. To investigate this process, we used a combination of in vivo imaging of kinesin heavy-chain Kif5c (an isoform of kinesin-1) fused to GFP, in vitro analyses and mathematical modelling. GFP-Kif5c fluorescent puncta localised to a subset of microtubules in live cells. These puncta moved at speeds of up to 1 m second -1 and exchanged into cortically labelled clusters at microtubule ends. This behaviour depended on the presence of a functional motor domain, because a rigor-mutant GFP-Kif5c bound to microtubules but did not move along them. Further analysis indicated that the microtubule subset decorated by GFP-Kif5c was highly stable and primarily composed of detyrosinated tubulin. In vitro motility assays showed that the motor domain of Kif5c moved detyrosinated microtubules at significantly lower velocities than tyrosinated (unmodified) microtubules. Mathematical modelling predicted that a small increase in detyrosination would bias kinesin-1 occupancy towards detyrosinated microtubules. These data suggest that kinesin-1 preferentially binds to and trafficks on detyrosinated microtubules in vivo, providing a potential basis for the spatial targeting of kinesin-1-based cargo transport. Supplementary material available online at

Cytosolic Carboxypeptidase 1 Is Involved in Processing α- and β-Tubulin

“…Tubulin modifications are important for the affinity of motors and thus intracellular transport of the cellular cargoes. It was shown that the molecular motor kinesin binds preferentially to deTyr-tubulin to efficiently transport cargo (50,51). Disruption of tubulin dynamics can cause mitochondrial dysfunction and lead to neurodegeneration (52).…”

Trafficking Guidance Receptors

“…In addition, microtubules carrying posttranslational modifications, such as tyrosination/detyrosination, show preferential interactions with certain KIFs. KIF5C, for example, preferentially binds detyrosinated and acetylated microtubules (Dunn et al 2008). It was shown recently in fact that loss of the tubulin tyrosinase enzyme causes loss of neuronal polarity with many neurons elaborating multiple tau-positive processes (Konishi and Setou 2009).…”

Unique Post-Translational Modifications in Specialized Microtubule Architecture

“…Kinesin-1 shows more strong binding affinity to MT enriched by detyrosinated tubulin in vitro (Liao and Gundersen, 1998). In vivo, kinesin-1 preferentially binds to detyrosinated tubulin-rich MTs (Dunn et al, 2008). Kinesin-1 selectively accumulates in a future axon in early stage of neuronal growth (Jacobson et al, 2006).…”