Cavities in Context: Distinct Consequences of Packing Defects in a Repeat Protein Folding Landscape

Extant protein sequences are the result of evolutionary pressure. It is likely that proteins have evolved to exhibit optimal levels of conformational heterogeneity and dynamics in the context of allosteric regulation of their function, proteostasis and cellular localization. While the effects of changing amino acid sequence on protein global structure can often be predicted, at least qualitatively, the rules governing how sequence modulates protein conformational landscapes is not well understood, likely because protein excited states are difficult to populate and characterize. Pressure perturbation acts locally to eliminate internal solvent excluded void volume in proteins, and this favors the population of excited conformational states. Using pressure perturbation we examine how the introduction of packing defects modulates protein folding landscapes