肌动蛋白的枯草杆菌蛋白酶切割会抑制肌动蛋白丝在肌球蛋白上的体外滑动运动。
Subtilisin cleavage of actin inhibits in vitro sliding movement of actin filaments over myosin.
作者信息
Schwyter D H, Kron S J, Toyoshima Y Y, Spudich J A, Reisler E
机构信息
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
出版信息
J Cell Biol. 1990 Aug;111(2):465-70. doi: 10.1083/jcb.111.2.465.
Subtilisin cleaved actin was shown to retain several properties of intact actin including the binding of heavy meromyosin (HMM), the dissociation from HMM by ATP, and the activation of HMM ATPase activity. Similar Vmax but different Km values were obtained for acto-HMM ATPase with the cleaved and intact actins. The ATPase activity of HMM stimulated by copolymers of intact and cleaved actin showed a linear dependence on the fraction of intact actin in the copolymer. The most important difference between the intact and cleaved actin was observed in an in vitro motility assay for actin sliding movement over an HMM coated surface. Only 30% of the cleaved actin filaments appeared mobile in this assay and moreover, the velocity of the mobile filaments was approximately 30% that of intact actin filaments. These results suggest that the motility of actin filaments can be uncoupled from the activation of myosin ATPase activity and is dependent on the structural integrity of actin and perhaps, dynamic changes in the actin molecule.
枯草杆菌蛋白酶切割的肌动蛋白被证明保留了完整肌动蛋白的几种特性，包括与重酶解肌球蛋白（HMM）的结合、通过ATP从HMM上解离以及激活HMM ATP酶活性。对于肌动蛋白-HMM ATP酶，用切割后的肌动蛋白和完整肌动蛋白得到了相似的Vmax但不同的Km值。由完整肌动蛋白和切割后的肌动蛋白共聚物刺激的HMM的ATP酶活性对共聚物中完整肌动蛋白的比例呈线性依赖。在肌动蛋白在HMM包被表面上滑动运动的体外运动分析中，观察到完整肌动蛋白和切割后的肌动蛋白之间最重要的差异。在该分析中，只有30%的切割后的肌动蛋白丝表现出可移动性，此外，可移动丝的速度约为完整肌动蛋白丝速度的30%。这些结果表明，肌动蛋白丝的运动性可以与肌球蛋白ATP酶活性的激活解偶联，并且依赖于肌动蛋白的结构完整性，也许还依赖于肌动蛋白分子的动态变化。
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