Basic Forestry and Proteomic Research Center, Fujian Provincial Key Laboratory of Plant Functional Biology, Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Haixia Institute of Sciences and Technology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
J Integr Plant Biol. 2022 Aug;64(8):1514-1530. doi: 10.1111/jipb.13281. Epub 2022 Jun 13.
The organization of the microtubule cytoskeleton is critical for cell and organ morphogenesis. The evolutionarily conserved microtubule-severing enzyme KATANIN plays critical roles in microtubule organization in the plant and animal kingdoms. We previously used conical cell of Arabidopsis thaliana petals as a model system to investigate cortical microtubule organization and cell morphogenesis and determined that KATANIN promotes the formation of circumferential cortical microtubule arrays in conical cells. Here, we demonstrate that the conserved protein phosphatase PP2A interacts with and dephosphorylates KATANIN to promote the formation of circumferential cortical microtubule arrays in conical cells. KATANIN undergoes cycles of phosphorylation and dephosphorylation. Using co-immunoprecipitation coupled with mass spectrometry, we identified PP2A subunits as KATANIN-interacting proteins. Further biochemical studies showed that PP2A interacts with and dephosphorylates KATANIN to stabilize its cellular abundance. Similar to the katanin mutant, mutants for genes encoding PP2A subunits showed disordered cortical microtubule arrays and defective conical cell shape. Taken together, these findings identify PP2A as a regulator of conical cell shape and suggest that PP2A mediates KATANIN phospho-regulation during plant cell morphogenesis.
微管细胞骨架的组织对于细胞和器官形态发生至关重要。进化上保守的微管切割酶 KATANIN 在植物和动物王国的微管组织中发挥着关键作用。我们之前使用拟南芥花瓣的锥形细胞作为模型系统来研究皮质微管组织和细胞形态发生，并确定 KATANIN 促进锥形细胞中环形皮质微管阵列的形成。在这里，我们证明保守的蛋白磷酸酶 PP2A 与 KATANIN 相互作用并使其去磷酸化，以促进锥形细胞中环形皮质微管阵列的形成。KATANIN 经历磷酸化和去磷酸化的循环。通过免疫共沉淀结合质谱分析，我们鉴定出 PP2A 亚基是 KATANIN 的相互作用蛋白。进一步的生化研究表明，PP2A 与 KATANIN 相互作用并使其去磷酸化，从而稳定其细胞丰度。与 katanin 突变体类似，编码 PP2A 亚基的基因突变体显示出紊乱的皮质微管阵列和锥形细胞形状缺陷。总之，这些发现确定了 PP2A 是锥形细胞形状的调节剂，并表明 PP2A 在植物细胞形态发生过程中介导 KATANIN 的磷酸化调节。
