De novo designed ice-binding proteins from twist-constrained helices

Abstract

Attaining molecular-level control over solidification processes is a crucial aspect of materials science. To control ice formation, organisms have evolved bewildering arrays of ice-binding proteins (IBPs) but these have poorly understood structure-activity relationships. We propose that reverse engineering using de novo computational protein design can shed light on structure-activity relationships of IBPs. We hypothesized that the model alpha-helical winter flounder antifreeze protein (wfAFP) uses an unusual under-twisting of its alpha-helix to align its putative ice-binding threonine residues in exactly the same direction. We test this hypothesis by designing a series of straight three-helix bundles with an ice-binding helix projecting threonines and two supporting helices constraining the twist of the ice-binding helix. We find that ice recrystallization inhibition by the designed proteins increases with the degree of designed under-twisting, thus validating our hypothesis and opening up new avenues for the computational design of ice-binding proteins.

Flat Solenoidal Ice‐Binding Proteins as Scaffolds for Solid‐Binders

“…One recent example is the de novo design of alpha-helical repeat proteins geometrically matched to the potassium ion (K+) sublattice on muscovite mica (001) [12] and more recently the de novo design of ice-binding proteins from twist-constrained helices. [13] Another protein topology with the potential to form extended flat faces that could precisely interact with crystal planes of solid materials, are β-solenoids. So far, a completely de novo design of a repetitive β-solenoid has not been reported yet, but there are many natural templates that could be suitable starting points for computational re-design.…”