Poster abstracts

Poster number 34 submitted by Eric Hantz

An Adaptative Steered Molecular Dynamics (ASMD) study of mutagenesis effects on calcium binding in the regulatory domain of cardiac troponin C

Eric Hantz (The Ohio State University)

Abstract:
Calcium-dependent cardiac muscle contraction is regulated by the protein complex troponin (cTn). The regulatory, N-terminal domain (N-cTnC) contains one active binding site (site II), which has been characterized as having low affinity and high selectivity to Ca2+ 1-3. Cardiac muscle contractility and functionality has been shown to be affected by mutations in the regulatory domain of cTnC. The mutations either increase or decrease Ca2+ binding based on the substituted residue identity and their locations in the tertiary structure relative to site II 4. Here, we employed an adaptive steered molecular dynamics (ASMD) methodology to reproduce experimental results of known Ca2+ binding altering mutants. We found that the calculated ∆∆G values correlated well with experimental findings for all mutants variants. In addition, potential of mean force (PMF) convergence was achieved quickly with minimal trajectories approaching infinitely slow pulling rates. In conclusion, this study presents a novel approach to calculating the Ca2+ binding affinity of N-cTnC structures and is a valuable potential tool to support the design and characterization of novel mutations with potential therapeutic benefits.

References:
1.Li, M. X.; Hwang, P. M., Structure and function of cardiac troponin C (TNNC1): Implications for heart failure, cardiomyopathies, and troponin modulating drugs. Gene 2015, 571 (2), 153-66.
2.Marston, S.; Zamora, J. E., Troponin structure and function: a view of recent progress. J Muscle Res Cell Motil 2019.
3.Sia, S. K.; Li, M. X.; Spyracopoulos, L.; Gagné, S. M.; Liu, W.; Putkey, J. A.; Sykes, B. D., Structure of cardiac muscle troponin C unexpectedly reveals a closed regulatory domain. J Biol Chem 1997, 272 (29), 18216-21.
4.Tikunova, S. B.; Davis, J. P., Designing calcium-sensitizing mutations in the regulatory domain of cardiac troponin C. J Biol Chem 2004, 279 (34), 35341-52.

Keywords: Troponin , Adaptive Steered Molecular Dynamics, ASMD