Collisions of Cortical Microtubules with Membrane Associated Myosin VIII Tail.

Sefi Bar-Sinai,Vikas Dwivedi,Eduard Belausov,Einat Sadot

doi:10.3390/cells11010145

Abstract

The distribution of myosin VIII ATM1 tail in association with the plasma membrane is often observed in coordination with that of cortical microtubules (MTs). The prevailing hypothesis is that coordination between the organization of cortical MTs and proteins in the membrane results from the inhibition of free lateral diffusion of the proteins by barriers formed by MTs. Since the positioning of myosin VIII tail in the membrane is relatively stable, we ask: can it affect the organization of MTs? Myosin VIII ATM1 tail co-localized with remorin 6.6, the position of which in the plasma membrane is also relatively stable. Overexpression of myosin VIII ATM1 tail led to a larger fraction of MTs with a lower rate of orientation dispersion. In addition, collisions between MTs and cortical structures labeled by ATM1 tail or remorin 6.6 were observed. Collisions between EB1 labeled MTs and ATM1 tail clusters led to four possible outcomes: 1—Passage of MTs through the cluster; 2—Decreased elongation rate; 3—Disengagement from the membrane followed by a change in direction; and 4—retraction. EB1 tracks became straighter in the presence of ATM1 tail. Taken together, collisions of MTs with ATM1 tail labeled structures can contribute to their coordinated organization.

Highlights

The plant MTs cytoskeleton is organized into two main structures: during cell division, it forms the cell-division apparatus, which is sequentially developed from the preprophase band, to the spindle and the phragmoplast; during interphase, MTs form parallel arrays under the plasma membrane [1,2,3,4]
ATM1IQ-tail is associated with the plasma membrane [22,23]
To check the nature of ATM1IQ-tail cortical clusters, we compared them to membrane proteins from the remorin family [37]

Summary

Introduction

The plant MTs cytoskeleton is organized into two main structures: during cell division, it forms the cell-division apparatus, which is sequentially developed from the preprophase band, to the spindle and the phragmoplast; during interphase, MTs form parallel arrays under the plasma membrane [1,2,3,4]. The retention of MTs at the cortex prevents their free lateral sliding and sinking deep into the cytoplasm Their stable positioning at the cortex is important for the cortical MTs’ role in directing the cellulose synthase complex (CSC) to entry sites in the plasma membrane [7,8], and in forming tracks for CSC trajectories in the plasma membrane while cellulose is deposited outside the cell [9]. It has been shown that severing at crossover points contributes to MTs reorientation [13,14]

Methods

Results

Conclusion