Correlated motions and propagation of the effect of a local conformational change in the transmembrane helix of the c-erb B2 encoded protein and its V659E mutant, studied by molecular dynamics simulations.

A detailed study of the dynamical behavior of the 29-residue peptide including the transmembrane domain of p185c-erbB2 oncogene-encoded protein and of its V659E mutant is presented. In a first part of this work we analyse equal time correlation coefficients between the backbone dihedral angle fluctuations. Concerted motions are observed in the wild type transmembrane alpha-helix but not in the corresponding V659E intramembrane domain. The difference observed in the correlation pattern is attributed to the single amino acid replacement. In a second part, we investigate the propagation of the effect of a local conformational change along the transmembrane segment, one of the dominant hypotheses for signal transduction mechanisms of transmembrane receptors. The analysis of angular time correlation functions together with that of the response of the different residues to a local disturbance applied at the N-terminal side evidences a propagation phenomenon for the wild type peptide. This effect is much less clear for the mutated peptide. Furthermore we show that the first one is much more flexible than the second one.