Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, Wageningen, 6708, PB, The Netherlands.
Cell Microbiol. 2014 Jun;16(6):948-61. doi: 10.1111/cmi.12254. Epub 2014 Jan 10.
The actin cytoskeleton is a dynamic but well-organized intracellular framework that is essential for proper functioning of eukaryotic cells. Here, we use the actin binding peptide Lifeact to investigate the in vivo actin cytoskeleton dynamics in the oomycete plant pathogen Phytophthora infestans. Lifeact-eGFP labelled thick and thin actin bundles and actin filament plaques allowing visualization of actin dynamics. All actin structures in the hyphae were cortically localized. In growing hyphae actin filament cables were axially oriented in the sub-apical region whereas in the extreme apex in growing hyphae, waves of fine F-actin polymerization were observed. Upon growth termination, actin filament plaques appeared in the hyphal tip. The distance between a hyphal tip and the first actin filament plaque correlated strongly with hyphal growth velocity. The actin filament plaques were nearly immobile with average lifetimes exceeding 1 h, relatively long when compared to the lifetime of actin patches known in other eukaryotes. Plaque assembly required ∼30 s while disassembly was accomplished in ∼10 s. Remarkably, plaque disassembly was not accompanied with internalization and the formation of endocytic vesicles. These findings suggest that the functions of actin plaques in oomycetes differ from those of actin patches present in other organisms.
肌动蛋白细胞骨架是一种动态但组织良好的细胞内框架，对于真核细胞的正常功能至关重要。在这里，我们使用肌动蛋白结合肽 Lifeact 来研究卵菌植物病原体致病疫霉中的体内肌动蛋白细胞骨架动力学。Lifeact-eGFP 标记的厚肌动蛋白和薄肌动蛋白束以及肌动蛋白丝斑，允许可视化肌动蛋白动力学。菌丝中的所有肌动蛋白结构都定位于皮质。在生长的菌丝中，肌动蛋白丝电缆在亚顶端区域轴向定向，而在生长的菌丝的极端顶端，观察到细 F-肌动蛋白聚合的波动。在生长终止时，在菌丝尖端出现肌动蛋白丝斑。菌丝尖端和第一个肌动蛋白丝斑之间的距离与菌丝生长速度密切相关。肌动蛋白丝斑几乎不动，平均寿命超过 1 小时，与其他真核生物中已知的肌动蛋白斑的寿命相比相对较长。斑块组装需要约 30 秒，而解组装在约 10 秒内完成。值得注意的是，斑块解组装不伴有内化和形成内吞小泡。这些发现表明，卵菌中的肌动蛋白斑的功能与其他生物体中存在的肌动蛋白斑不同。
