The microtubule-nucleating factor MACERATOR tethers AUGMIN7 to microtubules and governs phragmoplast architecture
The microtubule-nucleating factor MACERATOR tethers AUGMIN7 to microtubules and governs phragmoplast architecture
复制标题
DOI：
10.1093/plcell/koad304
复制
发表时间：
2023-12-11
期刊：
影响因子：
11.6
通讯作者：
Smertenko，Andrei
中科院分区：
文献类型：
--
作者：
Schmidt-Marcec，Sharol;Parish，Alyssa;Smertenko，Andrei
植物细胞动力学微管阵列，称为成膜体，具有较高的微管动力学在其中心（中间区）比在周边（远端区）。这种行为被称为轴向不对称。尽管是成膜体的一个主要特征，但对这种现象的调节剂知之甚少。在这里，我们解决微管成核在轴向不对称的作用，通过表征MACERATOR（MACET）蛋白inArabidopsis thalianaandNicotiana benthamiana与遗传，生物化学和活细胞成像分析相结合，使用光转换微管探针，和建模。MAET旁系同源物在收缩的微管末端积聚并降低微管蛋白的OFF速率。MACET 4和MACET 5功能的丧失通过抑制中间区的微管动力学来消除轴向不对称性。MACET 4还使成膜体前缘的微管成核角变窄，并作为AUGMIN复合物亚基7（AUG 7）的微管束缚因子发挥作用。该acet 4 macet 5双突变体显示减少的成膜体远端区中的AUG 7的聚集。敲除AUG 7不影响MACET 4定位、轴向不对称性或微管成核角，但增加成膜体长度并减缓成膜体扩张。mce 4 -1 mce 5 aug 7 - 1三重敲除是不可行的。实验数据和建模表明，微管成核因子调节成膜体结构和轴向不对称性直接产生新的微管和间接通过调节游离微管蛋白的丰度。
The plant cytokinetic microtubule array, called the phragmoplast, exhibits higher microtubule dynamics in its center (midzone) than at the periphery (distal zone). This behavior is known as the axial asymmetry. Despite being a major characteristic of the phragmoplast, little is known about regulators of this phenomenon. Here we address the role of microtubule nucleation in axial asymmetry by characterizing MACERATOR (MACET) proteins inArabidopsis thalianaandNicotiana benthamianawith a combination of genetic, biochemical, and live-cell imaging assays, using photo-convertible microtubule probes, and modeling. MACET paralogs accumulate at the shrinking microtubule ends and decrease the tubulin OFF rate. Loss of MACET4 and MACET5 function abrogates axial asymmetry by suppressing microtubule dynamicity in the midzone. MACET4 also narrows the microtubule nucleation angle at the phragmoplast leading edge and functions as a microtubule tethering factor for AUGMIN COMPLEX SUBUNIT 7 (AUG7). Themacet4 macet5double mutant shows diminished clustering of AUG7 in the phragmoplast distal zone. Knockout ofAUG7does not affect MACET4 localization, axial asymmetry, or microtubule nucleation angle, but increases phragmoplast length and slows down phragmoplast expansion. Themce4-1 mce5 aug7-1triple knockout is not viable. Experimental data and modeling demonstrate that microtubule nucleation factors regulate phragmoplast architecture and axial asymmetry directly by generating new microtubules and indirectly by modulating the abundance of free tubulin.