Siddique Md Shahjahan P, Miyazaki Takashi, Katayama Eisaku, Uyeda Taro Q P, Suzuki Makoto
Department of Materials Processing, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579, Japan.
Biochem Biophys Res Commun. 2005 Jul 1;332(2):474-81. doi: 10.1016/j.bbrc.2005.04.152.
We have engineered acto-S1chimera proteins carrying the entire actin inserted in loop 2 of the motor domain of Dictyostelium myosin II with 24 or 18 residue-linkers (CP24 and CP18, respectively). These proteins were capable of self-polymerization as well as copolymerization with skeletal actin and exhibited rigor-like structures. The MgATPase rate of CP24-skeletal actin copolymer was 1.06 s(-1), which is slightly less than the V(max) of Dictyostelium S1. Homopolymer filaments of skeletal actin, CP24, and CP18 moved at 4.7+/-0.6, 2.9+/-0.6, and 4.1+/-0.8 microm/s (mean+/-SD), respectively, on coverslips coated with skeletal myosin at 27 degrees C. Statistically thermodynamic considerations suggest that the S1 portion of chimera protein mostly resides on subdomain 1 (SD-1) of the actin portion even in the presence of ATP. This and the fact that filaments of CP18 with shorter linkers moved faster than CP24 filaments suggest that SD-1 might not be as essential as conventionally presumed for actomyosin sliding interactions.
我们构建了肌动蛋白 - S1嵌合蛋白，其携带插入到盘基网柄菌肌球蛋白II运动结构域环2中的完整肌动蛋白，并带有24个或18个残基的连接子（分别为CP24和CP18）。这些蛋白能够自我聚合以及与骨骼肌肌动蛋白共聚，并呈现出类似僵直的结构。CP24 - 骨骼肌肌动蛋白共聚物的MgATPase速率为1.06 s(-1)，略低于盘基网柄菌S1的V(max)。在27摄氏度下，骨骼肌肌动蛋白、CP24和CP18的同聚物细丝在涂有骨骼肌肌球蛋白的盖玻片上分别以4.7±0.6、2.9±0.6和4.1±0.8微米/秒（平均值±标准差）的速度移动。统计热力学考虑表明，即使在有ATP存在的情况下，嵌合蛋白的S1部分大多位于肌动蛋白部分的亚结构域1（SD - 1）上。这一点以及带有较短连接子的CP18细丝比CP24细丝移动得更快这一事实表明，对于肌动球蛋白滑动相互作用而言，SD - 1可能不像传统推测的那样至关重要。
