Abstract：
The mechanisms that ensure proper assembly, activity, and turnover of myosin II filaments are fundamental to a diverse range of cellular processes. In Caenorhabditis elegans striated muscle, thick filaments contain two myosins that are functionally distinct and spatially segregated. Using transgenic double mutants, we demonstrate that the ability of increased myosin A expression to restore muscle structure and movement in myosin B mutants requires UNC-82/NUAK kinase activity. Myosin B function appears unaffected in the kinase-impaired unc-82(e1220) mutant: the recessive antimorphic effects on early assembly of paramyosin and myosin A in this mutant are counteracted by increased myosin B expression and exacerbated by loss of myosin B. Using chimeric myosins and motility assays, we mapped the region of myosin A that requires UNC-82 activity to a 531-amino-acid region of the coiled-coil rod. This region includes the 264-amino-acid Region 1, which is sufficient in chimeric myosins to rescue the essential filament-initiation function of myosin A, as well as two sites that interact with myosin head domains in the Interacting Heads Motif. A specific physical interaction between myosin A and UNC-82::GFP is supported by GFP labeling of ectopic myosin A filaments but not thin filaments. We hypothesize that UNC-82 regulates assembly competence of myosin A during parallel assembly in the filament arms.
摘要：
确保适当装配的机制，活动,肌球蛋白II细丝的周转是各种细胞过程的基础。秀丽隐杆线虫横纹肌,粗丝包含两种功能不同且空间分离的肌球蛋白。使用转基因双突变体，我们证明了肌球蛋白A表达增加以恢复肌球蛋白B突变体的肌肉结构和运动的能力需要UNC-82/NUAK激酶活性。肌球蛋白B的功能在激酶受损的unc-82（e1220）突变体中似乎不受影响：在该突变体中，对副肌球蛋白和肌球蛋白A早期组装的隐性反常作用被肌球蛋白B表达的增加所抵消，并因肌球蛋白B的丢失而加剧。使用嵌合肌球蛋白和运动性测定，我们将需要UNC-82活性的肌球蛋白A区域映射到卷曲螺旋棒的531个氨基酸区域。该区域包括264个氨基酸的区域1，该区域在嵌合肌球蛋白中足以挽救肌球蛋白A的基本细丝起始功能，以及与“交互头”主题中的肌球蛋白头域相互作用的两个站点。肌球蛋白A和UNC-82::GFP之间的特定物理相互作用由异位肌球蛋白A细丝而不是细丝的GFP标记支持。我们假设UNC-82在细丝臂的平行组装过程中调节肌球蛋白A的组装能力。
