Creating a ‘Molecular Band-Aid’; Blocking an Exposed Protease Target Site in Desmoplakin

• Main Authors: Catherine A. Hoover, Kendahl L. Ott, Heather R. Manring, Trevor Dew, Maegen A. Borzok, Nathan T. Wright
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Journal of Personalized Medicine
• Subjects: desmoplakin; molecular dynamics; calpain; arrhythmogenic cardiomyopathy
• Online Access: https://www.mdpi.com/2075-4426/11/5/401

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 NH₂-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.