Yeast actin filaments display ATP-dependent sliding movement over surfaces coated with rabbit muscle myosin.

The yeast Saccharomyces cerevisiae has been used to study the function of components of the actin cytoskeleton in vivo, mainly because it is easy to derive and characterize mutations affecting these proteins. In contrast, biochemical studies have generally used proteins derived from higher eukaryotes. We have devised a simple procedure to prepare, in high yield, homogeneous native actin from wild-type and act1 mutant yeast. Using intensified video fluorescence microscopy, we found that actin filaments polymerized from these preparations exhibit ATP-dependent sliding movement over surfaces coated with rabbit skeletal muscle myosin. The rates of sliding movement of the wild-type and mutant yeast actins were each about half that of rabbit skeletal muscle actin under similar conditions. We conclude that over the large evolutionary distance between yeast and mammals there has been significant conservation of actin function, specifically the ability to be moved by interaction with myosin.

酿酒酵母（Saccharomyces cerevisiae）已被用于在体内研究肌动蛋白细胞骨架成分的功能，这主要是因为它易于获得并鉴定影响这些蛋白质的突变。相比之下，生化研究通常使用来自高等真核生物的蛋白质。我们设计了一种简单的方法，能从野生型和act1突变型酵母中高产率地制备均一的天然肌动蛋白。通过增强视频荧光显微镜技术，我们发现由这些提取物聚合而成的肌动蛋白丝在涂有兔骨骼肌肌球蛋白的表面上呈现出依赖ATP的滑动运动。在相似条件下，野生型和突变型酵母肌动蛋白的滑动速率均约为兔骨骼肌肌动蛋白的一半。我们得出结论，在酵母和哺乳动物之间的巨大进化距离中，肌动蛋白的功能，特别是通过与肌球蛋白相互作用而移动的能力，具有显著的保守性。