Protein dynamics, folding, and thermodynamics represent a central aspect of biophysical chemistry. pH, temperature, and denaturant perturbations inform our understanding of diverse contributors to stability and rates. In this work, a thermodynamic analysis using a combined experimental and computational approach to gain insights into the role of electrostatics in the folding reaction of a psychrophile frataxin variant from Psychromonas ingrahamii. The folding reaction is strongly modulated by pH with a single, narrow and well-defined transition state with ~80% compactness, ~70% electrostatic interactions and ~60% hydration shell compared to the native state (αD=0.82, αH=0.67 and αΔCp=0.59). Molecular dynamics simulations showed that these pH modulation could be explained by the fluctuations of two regions, rich in electrostatic contacts, whose dynamics are pH-dependent and motions are strongly correlated. Results presented herein contribute to the understanding of the stability and dynamics of this frataxin variant, pointing to an intrinsic feature of the family topology to support different folding mechanism.
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