Structural Stability of Intelectin-1

We study the structural stability of helical and non-helical regions in chain A of human intelectin-1. Using a geometrical model introduced previously, a computational analysis based on the recently reported crystal structure of this protein by Kiessling et al. [Nature Struct. Mole. Bio. 22 (2015), 603] is carried out to quantify the resiliency of the native state to steric perturbations. Response to these perturbations is characterized by calculating, relative to the native state, the lateral, radial and angular displacements of n-residue segments of the polypeptide chain centered on each residue. By quantifying the stability of the protein through six stages of unfolding, we are able to identify regions in chain A of intelectin-1 which are markedly affected by structural perturbations versus those which are relatively unaffected, the latter suggesting that the native-state geometry of these regions is essentially conserved. Importantly, residues in the vicinity of calcium ions comprise a conserved region, suggesting that Ca ions play a role not only in the coordination of carbohydrate hydroxyl groups, but in preserving the integrity of the structure.