Protein electrostatics play an important role in both local and global dynamics, frequently influencing protein (un)folding, aggregation propensity, and ligand binding/affinity. In studying these biological processes, NMR is an optimal experimental approach as the sensitivity of NMR chemical shifts to both molecular composition and local environment allows for a comprehensive description of pH-dependent effects. Currently, empirical and semi-empirical chemical shift predictors are largely insensitive to extreme pH conditions and compute absolute shifts only at physiological pH. In previous work, we demonstrate that a combination of molecular dynamics and <i>ab initio </i>calculations can be utilized to recapitulate protonation dependent chemical shift perturbations (CSP) in model peptides. In this study we employ a similar approach to investigate electrostatically driven interactions in proteins. Hisactophilin presents a formidable test case, as this protein is rich in titratable residues and undergoes pH dependent conformational transitions impacting the accessibility of a functionally crucial myristoyl group. Of significant interest is the mechanism by which the protonation of key histidines impacts the myristoyl-switching ultimately facilitating membrane-binding. Broadly, we anticipate that the computation of the pH-dependent CSPs for this system, will lead to a generalized protocol through which these observables may be computed for a variety of proteins involved in pH-mediated processes.

Exploration of protein electrostatics through the interpretation of pH dependent NMR chemical shift perturbations

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.