Abstract：
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.
摘要：
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断酶KATANIN在动植物王国的微管组织中起着关键作用。我们先前使用拟南芥花瓣的圆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促进圆锥形细胞中环状皮质微管阵列的形成。这里,我们证明，保守的蛋白磷酸酶PP2A与KATANIN相互作用并去磷酸化，以促进锥形细胞中环状皮质微管阵列的形成。卡塔宁经历磷酸化和去磷酸化循环。使用免疫共沉淀与质谱联用，我们将PP2A亚基鉴定为KATANIN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，以稳定其细胞丰度。类似于katanin突变体，编码PP2A亚基的基因的突变体显示皮质微管阵列无序和圆锥形细胞形状缺陷。一起来看,这些发现确定PP2A是圆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磷酸化调节。
