Orienting new cell walls in Arabidopsis thaliana with kinesin-12 POK1 and POK2
Plant development and morphology relay on the accurate insertion of new cell walls during cytokinesis. However, how a plant cell correctly orients a growing cell wall is poorly understood. Two kinesin class-12 members, phragmoplast orienting kinesin 1 (POK1) and POK2, are involved in the process, but how these molecular machines work is not known. Using in vivo and single-molecule in vitro methods, we measured how Arabidopsis thaliana POK1 and POK2 motors function mechanically. We found that both POKs are plus-end directed kinesins that switch between processive and diffusive modes, however, to different extents. We have characterized the switching behaviour by a mutually exclusive-state mean-squared displacement analysis. Our results support a model that POK motors push against peripheral microtubules of the phragmoplast for its guidance. This pushing model may mechanically explain the conspicuous narrowing of the division site. Together, our findings provide mechanical insight into how active motors accurately position new cell walls in plants.
PhD Student, University of Tübingen, Germany
CNRS UMR3215/Inserm U934
Domain 2 - UMR 3215 / U934 - Genetics and Developmental Biology