The ARM domain of ARMADILLO-REPEAT KINESIS 1 is not required for microtubule catastrophe but can negatively regulate NIMA-RELATED KINASE 6 in Arabidopsis thaliana

ARMADILLO-REPEAT KINESIN 1 (ARK1) promotes microtubule disassembly and NIMA-RELATED KINASE 6 (NEK6) organizes microtubule arrays. Previous studies showed that NEK6 interacts with ARK1 through Armadillo-repeat (ARM) cargo domain. Eng et al. looked at two constructs: one which lacks ARM (ARK1▲ARM-GFP) and another one with only the ARM domain (ARM-GFP). Interestingly, the authors have found that ARK1▲ARM-GFP can induce microtubule disassenbly and rescue the ark1-1 root hair phenotype. This indicates that ARK1 doesn’t require the ARM domain or interaction with NEK6 to induce microtubule catastrophe. The authors conclude that ARK1 and NEK6 contribute to microtubule dynamics independently, and observe that NEK6 gene expression is blocked when ARK’s ARM domain is overexpressed, suggesting a relationship at the level of transcriptional regulation. This study was featured on the cover of Plant & Cell Physiology (Volume 58, Issue 8, August 2017). Plant Cell Physiol. 10.1093/pcp/pcx070