Fisher A J, Smith C A, Thoden J, Smith R, Sutoh K, Holden H M, Rayment I
Department of Biochemistry, University of Wisconsin, Madison 53705, USA.
Biophys J. 1995 Apr;68(4 Suppl):19S-26S; discussion 27S-28S.
The structures of the MgADP-beryllium fluoride and MgADP-aluminum fluoride complexes of the truncated myosin head from Dictyostelium myosin II are reported. These reveal the location of the nucleotide complex and define the amino acid residues that form the active site. The tertiary structure of the beryllium fluoride complex is essentially identical to that seen previously in the three-dimensional structure of chicken skeletal muscle myosin. By contrast, significant domain movements are observed in the aluminum fluoride complex. These structural findings form the basis of a revised model for the structural basis of the contractile cycle. It is now suggested that the narrow cleft that splits the central 50-kDa segment of the heavy chain provides not only the communication route between the nucleotide-binding pocket and actin but also transmits the conformational change necessary for movement.
报道了盘基网柄菌肌球蛋白II截短肌球蛋白头部的MgADP-氟化铍和MgADP-氟化铝复合物的结构。这些结构揭示了核苷酸复合物的位置，并确定了形成活性位点的氨基酸残基。氟化铍复合物的三级结构与先前在鸡骨骼肌肌球蛋白三维结构中观察到的基本相同。相比之下，在氟化铝复合物中观察到明显的结构域运动。这些结构发现构成了收缩循环结构基础的修订模型的基础。现在有人提出，将重链中央50 kDa片段分开的狭窄裂缝不仅提供了核苷酸结合口袋与肌动蛋白之间的通信途径，还传递了运动所需的构象变化。
