A Second Tubulin Binding Site on the Kinesin-13 Motor Head Domain Is Important during Mitosis

Dong Zhang,David J Sharp,Hernando Sosa,Luping Xie,Michaela Greenbaum,Ana B Asenjo,Maria Gasset

doi:10.1371/journal.pone.0073075

Dong Zhang, David J Sharp + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0073075

Copy DOI

Abstract

Kinesin-13s are microtubule (MT) depolymerases different from most other kinesins that move along MTs. Like other kinesins, they have a motor or head domain (HD) containing a tubulin and an ATP binding site. Interestingly, kinesin-13s have an additional binding site (Kin-Tub-2) on the opposite side of the HD that contains several family conserved positively charged residues. The role of this site in kinesin-13 function is not clear. To address this issue, we investigated the in-vitro and in-vivo effects of mutating Kin-Tub-2 family conserved residues on the Drosophila melanogaster kinesin-13, KLP10A. We show that the Kin-Tub-2 site enhances tubulin cross-linking and MT bundling properties of KLP10A in-vitro. Disruption of the Kin-Tub-2 site, despite not having a deleterious effect on MT depolymerization, results in abnormal mitotic spindles and lagging chromosomes during mitosis in Drosophila S2 cells. The results suggest that the additional Kin-Tub-2 tubulin biding site plays a direct MT attachment role in-vivo.

Highlights

Kinesin-13s are MT depolymerases [1] that modulate MT dynamics during important cellular processes such as mitosis [2], cytokinesis [3], axonal branching [4] and ciliogenesis [5]
Our results indicate that the unique Kin-Tub-2 site provides a MT attachment role independent of kinesin-13 MT depolymerization activity and that this binding site is important for proper spindle morphogenesis and poleward chromosome movement during mitosis
In previous work we found that kinesin-13s can form oligomeric rings and spirals around MTs, mediated by an additional tubulin binding site on the head domain (HD) that we called KinTub-2 [13] (Figure 1A)

Summary

Introduction

Kinesin-13s are MT depolymerases [1] that modulate MT dynamics during important cellular processes such as mitosis [2], cytokinesis [3], axonal branching [4] and ciliogenesis [5]. Our results indicate that the unique Kin-Tub-2 site provides a MT attachment role independent of kinesin-13 MT depolymerization activity and that this binding site is important for proper spindle morphogenesis and poleward chromosome movement during mitosis. It is interesting to note that another case of a positively charged Kin-Tub-2 site is found on the Kinesin-7, CENPE (Figure 1C), which is thought to have a MT attachment role and link chromosomes to spindle MTs [25,26,27].

Results

Conclusion