Hoover Catherine A, Ott Kendahl L, Manring Heather R, Dew Trevor, Borzok Maegen A, Wright Nathan T
Department of Natural Sciences, Mansfield University of Pennsylvania, Mansfield, PA 16933, USA.
Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA.
J Pers Med. 2021 May 12;11(5):401. doi: 10.3390/jpm11050401.
Desmoplakin (DSP) is a large (~260 kDa) protein found in the desmosome, a subcellular complex that links the cytoskeleton of one cell to its neighbor. A mutation 'hot-spot' within the NH-terminal third of the DSP protein (specifically, residues 299-515) is associated with both cardiomyopathies and skin defects. In select DSP variants, disease is linked specifically to the uncovering of a previously-occluded calpain target site (residues 447-451). Here, we partially stabilize these calpain-sensitive DSP clinical variants through the addition of a secondary single point mutation-tyrosine for leucine at amino acid position 518 (L518Y). Molecular dynamic (MD) simulations and enzymatic assays reveal that this stabilizing mutation partially blocks access to the calpain target site, resulting in restored DSP protein levels. This 'molecular band-aid' provides a novel way to maintain DSP protein levels, which may lead to new strategies for treating this subset of DSP-related disorders.
桥粒斑蛋白（DSP）是一种存在于桥粒中的大型蛋白质（约260 kDa），桥粒是一种将一个细胞的细胞骨架与其相邻细胞连接起来的亚细胞复合体。DSP蛋白N端三分之一区域内的一个突变“热点”（具体为第299 - 515位氨基酸残基）与心肌病和皮肤缺陷均有关联。在某些DSP变体中，疾病具体与一个先前被封闭的钙蛋白酶作用靶点（第447 - 451位氨基酸残基）的暴露有关。在此，我们通过添加一个二级单点突变——在第518位氨基酸处将亮氨酸替换为酪氨酸（L518Y），部分稳定了这些对钙蛋白酶敏感的DSP临床变体。分子动力学（MD）模拟和酶学分析表明，这种稳定突变部分阻碍了对钙蛋白酶作用靶点的 access ，从而使DSP蛋白水平得以恢复。这种“分子创可贴”提供了一种维持DSP蛋白水平的新方法，这可能会带来治疗这一亚型DSP相关疾病的新策略。
