Microtubule- and actin filament-dependent motors are distributed on pollen tube mitochondria and contribute differently to their movement
Microtubule- and actin filament-dependent motors are distributed on pollen tube mitochondria and contribute differently to their movement
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DOI：
10.1093/pcp/pcm001
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发表时间：
2007-02-01
影响因子：
4.9
通讯作者：
Cresti, Mauro
中科院分区：
文献类型：
--
作者：
Romagnoli, Silvia;Cai, Giampiero;Cresti, Mauro
花粉管细胞器的细胞质流动依赖于肌动蛋白-肌球蛋白系统。虽然微管为基础的电机也已确定在花粉管中，许多不确定性存在关于它们在细胞器运输的作用。作为我们试图了解微管为基础的运动在烟草花粉管中的作用的一部分，我们研究了微管和肌动蛋白丝之间的合作，在运输线粒体和高尔基体囊泡，这是不同的分布在不断增长的花粉管。使用体外运动性测定进行分析，其中细胞器沿微管和肌动蛋白丝沿着移动。结果表明，线粒体和高尔基体囊泡沿沿着微管的运动是缓慢而连续的，而沿沿着肌动蛋白丝的运动是快速而不规则的。此外，运动性测定中微管的存在迫使细胞器使用较低的速度。肌动蛋白和微管蛋白结合试验，免疫印迹和免疫金标记表明，不同的细胞器结合相同的肌球蛋白，但与特定的驱动蛋白。我们发现，一个90 kDa的驱动蛋白（以前称为90 kDa的ATP-MAP）与线粒体，但不与高尔基体囊泡，而170 kDa的肌球蛋白分布在线粒体和其他细胞器类。在体外和体内运动性测定表明，微管和驱动蛋白降低线粒体的速度，从而有助于他们在花粉管中的定位。
The pollen tube exhibits cytoplasmic streaming of organelles, which is dependent on the actin-myosin system. Although microtubule-based motors have also been identified in the pollen tube, many uncertainties exist regarding their role in organelle transport. As part of our attempt to understand the role of microtubule-based movement in the pollen tube of tobacco, we investigated the cooperation between microtubules and actin filaments in the transport of mitochondria and Golgi vesicles, which are distributed differently in the growing pollen tube. The analysis was performed using in vitro motility assays in which organelles move along both microtubules and actin filaments. The results indicated that the movement of mitochondria and Golgi vesicles is slow and continuous along microtubules but fast and irregular along actin filaments. In addition, the presence of microtubules in the motility assays forces organelles to use lower velocities. Actin- and tubulin-binding tests, immunoblotting and immunogold labeling indicated that different organelles bind to identical myosins but associate with specific kinesins. We found that a 90 kDa kinesin (previously known as 90 kDa ATP-MAP) is associated with mitochondria but not with Golgi vesicles, whereas a 170 kDa myosin is distributed on mitochondria and other organelle classes. In vitro and in vivo motility assays indicate that microtubules and kinesins decrease the speed of mitochondria, thus contributing to their positioning in the pollen tube.