Conformational dynamics is more important than helical propensity for the folding of the all α-helical protein Im7.

ABSTRACT: Im7 folds via an on-pathway intermediate that contains three of the four native α-helices. The missing helix, helix III, is the shortest and its failure to be formed until late in the pathway is related to frustration in the structure. Im7H3M3, a 94-residue variant of the 87-residue Im7 in which helix III is the longest of the four native helices, also folds via an intermediate. To investigate the structural basis for this we calculated the frustration in the structure of Im7H3M3 and used NMR to investigate its dynamics. We found that the native state of Im7H3M3 is highly frustrated and in equilibrium with an intermediate state that lacks helix III, similar to Im7. Model-free analysis identified residues with chemical exchange contributions to their relaxation that aligned with the residue

SUBMITTER: Figueiredo AM 

PROVIDER: S-EPMC3843627 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature