Microtubule-Associated Kinase-like Protein RUNKEL Needed for Cell Plate Expansion in Arabidopsis Cytokinesis

摘要: Summary Cytokinesis partitions the cytoplasm of dividing eukaryotic cells. In higher plants, a dynamic microtubule array—phragmoplast—mediates formation partitioning membrane—cell plate—in centrifugal fashion [1, 2]. This phragmoplast involves microtubule-associated proteins [3–7]. Mutations in novel Arabidopsis gene RUNKEL ( RUK ) result cytokinesis defects caused by abnormal organization and arrested cell plate expansion. encodes an essential cell-cycle-regulated 152 kDa protein with putative serine/threonine kinase domain large microtubule-binding domain, both which are largely conserved uncharacterized from protozoa, animals. directly bound to microtubules in vitro colocalized mitotic preprophase band, spindle, in vivo. An engineered fusion that was degraded before telophase did not rescue ruk mutant phenotype, demonstrating action during cytokinesis. Both were for function. Surprisingly, show activity in vitro, transgenically expressed "kinase-dead" rescued seedling lethality mutants. Our results suggest plays regulatory, rather than catalytic, role expansion