Identification of the minimal protein-folding nucleus through loop-entropy perturbations.

ABSTRACT: To explore the plasticity and structural constraints of the protein-folding nucleus we have constructed through circular permutation four topological variants of the ribosomal protein S6. In effect, these topological variants represent entropy mutants with maintained spatial contacts. The proteins were characterized at two complementary levels of detail: by phi-value analysis estimating the extent of contact formation in the transition-state ensemble and by Hammond analysis measuring the site-specific growth of the folding nucleus. The results show that, although the loop-entropy alterations markedly influence the appearance and structural location of the folding nucleus, it retains a common motif of one helix docking against two strands. This nucleation motif is built around a shared subs

SUBMITTER: Lindberg MO 

PROVIDER: S-EPMC1449650 | biostudies-literature | 2006 Mar

REPOSITORIES: biostudies-literature