Computational exploration of TITIN variations: insights from whole exome sequencing and molecular dynamics simulation...

Titin (TTN), the largest known human protein (∼4 MDa), is considered as a key component for sarcomere integrity and function. Mutations in the TTN gene play a pivotal role in the genetic underpinnings of Dilated Cardiomyopathy (DCM). In the present study, we have conducted whole exome sequencing (WES) on 15 patients (5 familial and 10 sporadic) diagnosed with idiopathic DCM and identified 88 exonic variants. Here, we also report for the first time four novel variants comprising two frame-shifts, one missense, and one stop-codon variant. These variants are predominantly located in the A-band region (39 variants) of TTN, a critical region for its mechanical stability and interaction with other sarcomeric proteins, followed by the I-band domain (33 variants), Z-disc domain (7 variants), and M-band region (9 variants). To discern the functional repercussions of these variations, we have performed several bioinformatics analyses including pathogenicity prediction, protein stability, and protein-protein docking followed by molecular dynamics (MD) simulations on both wild-type and mutant TTN fragments with their corresponding interacting partners. We reveal that variations in the A-band domain significantly alter the protein's structural dynamics, leading to decreased mechanical stability and altered protein-protein interactions. These changes are likely to disrupt sarcomere function, thereby elucidating their role in the pathogenesis of DCM.