Amide hydrogen exchange and internal dynamics in the chemotactic protein CheY from Escherichia coli.

摘要: The backbone internal dynamics of the wild-type 129 amino acid alpha/beta parallel protein CheY and its double mutant F14N/P110G are analysed here by hydrogen-exchange method. F14N mutation is known to stabilise accelerate refolding while P110G destabilising accelerates unfolding. We first assigned characterised nuclear magnetic resonance (NMR), try discover any possible conformational change induced two mutations. main difference between proteins a favourable N-capping interaction newly introduced Asn14 side-chain at beginning alpha-helix (alpha-helix A). Second, we have measured exchange rates in CheY. In case observed protection factors slightly dispersed around an average value. According their distribution structure, stability highest on one face central beta-sheet, surroundings hydrophobic core formed side-chains residues beta-strands I, II III helices A E. mutations affect distinct subdomains differently (from beta-strand I from C end). second subdomain number protected protons reduced with respect those wild-type. This differential behaviour can be explained selective decrease folding produced opposite effect subdomain, mutation. alpha-Helix A, which involved together nucleus CheY, shows largest both proteins.