Sean S. C. Edington, Ph.D.
Ion signaling proteins regulate essential physiological processes by selectively binding specific ions and converting ion occupancy into conformational change. In cardiac signaling proteins, disease-associated mutations can alter structural kinetics even when equilibrium structures and binding affinities appear normal, leaving an important mechanism of cardiomyopathy unresolved. The long-term goal of this research program is to characterize how ion binding, protein structure, and conformational kinetics regulate cardiac signaling proteins such as cardiac troponin C. The objective of this project is to establish calibrated infrared spectroscopic methods and proof-of-concept datasets needed for future mechanistic studies of mutation-associated cardiomyopathy. The central hypothesis is that small perturbations near ion-binding sites can produce large changes in conformational kinetics despite minimal effects on equilibrium binding or structure.
This hypothesis will be tested using FTIR spectroscopy, quantum cascade laser time-resolved infrared spectroscopy, isothermal titration calorimetry, and molecular dynamics simulations. Aim 1 will use lanthanide binding tags as model systems to establish infrared markers of binding-site geometry, backbone structure, thermodynamic stability, and structural kinetics. Aim 2 will extend these measurements to S100G, a soluble monomeric EF-hand Ca² -binding protein, to determine how native ⁺ and non-native ion occupancy alter binding-site structure, thermal stability, and conformational remodeling rates. The expected outcome is an integrated spectroscopic, thermodynamic, kinetic, and computational framework for measuring how ion-binding sites control protein structural dynamics. This work is significant because it addresses a poorly resolved kinetic dimension of Ca²⁺-signaling dysfunction and will provide preliminary data and validated methods for future studies of cardiac troponin C mutations linked to cardiomyopathy.
Malfunctions in ion signaling proteins that control cardiac contraction cause some forms of heart disease. This project will develop infrared spectroscopic and computational approaches to determine how ion binding sites regulate protein structure and motion. These studies will provide a foundation for understanding mutation-associated cardiac signaling dysfunction and support future strategies for treating cardiomyopathy and related diseases.
