Allwood Ellen G, Anthony Richard G, Smertenko Andrei P, Reichelt Stefanie, Drobak Bjorn K, Doonan John H, Weeds Alan G, Hussey Patrick J
Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
Plant Cell. 2002 Nov;14(11):2915-27. doi: 10.1105/tpc.005363.
Pollen tube growth is dependent on a dynamic actin cytoskeleton, suggesting that actin-regulating proteins are involved. We have examined the regulation of the lily pollen-specific actin-depolymerizing factor (ADF) LlADF1. Its actin binding and depolymerizing activity is pH sensitive, inhibited by certain phosphoinositides, but not controlled by phosphorylation. Compared with its F-actin binding properties, its low activity in depolymerization assays has been used to explain why pollen ADF decorates F-actin in pollen grains. This low activity is incompatible with a role in increasing actin dynamics necessary to promote pollen tube growth. We have identified a plant homolog of actin-interacting protein, AIP1, which enhances the depolymerization of F-actin in the presence of LlADF1 by approximately 60%. Both pollen ADF and pollen AIP1 bind F-actin in pollen grains but are mainly cytoplasmic in pollen tubes. Our results suggest that together these proteins remodel actin filaments as pollen grains enter and exit dormancy.
花粉管的生长依赖于动态的肌动蛋白细胞骨架，这表明肌动蛋白调节蛋白参与其中。我们研究了百合花粉特异性肌动蛋白解聚因子（ADF）LlADF1的调节机制。其肌动蛋白结合和解聚活性对pH敏感，受某些磷酸肌醇抑制，但不受磷酸化控制。与其F-肌动蛋白结合特性相比，其在解聚试验中的低活性被用来解释为什么花粉ADF会在花粉粒中修饰F-肌动蛋白。这种低活性与促进花粉管生长所需的增加肌动蛋白动力学的作用不相符。我们鉴定出一种肌动蛋白相互作用蛋白AIP1的植物同源物，在LlADF1存在的情况下，它能将F-肌动蛋白的解聚增强约60%。花粉ADF和花粉AIP1都能在花粉粒中结合F-肌动蛋白，但在花粉管中主要位于细胞质中。我们的结果表明，当花粉粒进入和退出休眠时，这些蛋白质共同重塑肌动蛋白丝。
