Mechanical Strength of the Titin Z1Z2-Telethonin Complex

• DOI: 10.1016/j.str.2005.12.005
• Publication Date: 2006-03-15T12:41:16Z
• Authors: Eric H. Lee; Mu Gao; Nikos Pinotsis; Matthias Wilmanns; Klaus Schulten
• Keywords: Models, Molecular; Sarcomeres; Protein Folding; HUMDISEASE; Muscle Proteins; connectin; Sarcomeres: chemistry; Protein Structure, Secondary; Structure-Activity Relationship; 03 medical and health sciences; Structural Biology; Computer Simulation; Connectin; Protein Kinases: chemistry; Molecular Biology; info:eu-repo/classification/ddc/570; 0303 health sciences; Protein Kinases: metabolism; TCAP protein, human; Binding Sites; Muscle Proteins: chemistry; Hydrogen Bonding; Muscle Proteins: genetics; Protein Structure, Tertiary; CELLBIO; Stress, Mechanical; Muscle Proteins: metabolism; Dimerization; Protein Kinases; Protein Binding

Using molecular dynamics simulations, we have explored the mechanical strength of the titin Z1Z2-telethonin complex, namely, its ability to bear strong forces such as those encountered during passive muscle stretch. Our results show that not only does this complex resist considerable mechanical force through beta strand crosslinking, suggesting that telethonin is an important component of the N-terminal titin anchor, but also that telethonin distributes these forces between its two joined titin Z2 domains to protect the proximal Z1 domains from bearing too much stress. Our simulations also reveal that without telethonin, apo-titin Z1Z2 exhibits significantly decreased resistance to mechanical stress, and that the N-terminal segment of telethonin (residues 1-89) does not exhibit a stable fold conformation when it is unbound from titin Z1Z2. Consequently, our study sheds light on a key but little studied architectural feature of biological cells-the existence of strong mechanical links that glue separate proteins together.