Yokoyama Keiichi, Hiratuka Yuichi, Akimaru Erika, Hirose Keiko, Uyeda Taro Q P, Suzuki Makoto
Department of Metallurgy, Graduate School of Engineering, Tohoku University, Aramaki-aza-Aoba 02, Aobaku, Sendai 980-8579, Japan.
Biochem Biophys Res Commun. 2002 Dec 20;299(5):825-31. doi: 10.1016/s0006-291x(02)02758-4.
To gain more structural and functional information on the actomyosin complexes, we have engineered chimera proteins carrying the entire Dictyostelium actin in the loop 2 sequence of the motor domain of Dictyostelium myosin II. Although the chimera proteins were unable to polymerize by themselves, addition of skeletal actin promoted polymerization. Electron microscopic observation demonstrated that the chimera proteins were incorporated into actin filaments, when copolymerized with skeletal actin. Copolymerization with skeletal actin greatly enhanced the MgATPase, while the chimera proteins without added skeletal actin hydrolyzed ATP at a very low rate. These results indicate that the actin part and the motor domain part of the chimera proteins are correctly folded, but the chimera proteins are structurally stressed so that efficient polymerization is inhibited.
为了获得更多关于肌动球蛋白复合物的结构和功能信息，我们构建了嵌合蛋白，该蛋白在盘基网柄菌肌球蛋白II的马达结构域的环2序列中携带完整的盘基网柄菌肌动蛋白。尽管嵌合蛋白自身无法聚合，但添加骨骼肌肌动蛋白可促进聚合。电子显微镜观察表明，当与骨骼肌肌动蛋白共聚时，嵌合蛋白被整合到肌动蛋白丝中。与骨骼肌肌动蛋白共聚极大地增强了MgATP酶活性，而未添加骨骼肌肌动蛋白的嵌合蛋白水解ATP的速率非常低。这些结果表明，嵌合蛋白的肌动蛋白部分和马达结构域部分正确折叠，但嵌合蛋白在结构上受到压力，从而抑制了有效的聚合。
