SECONDARY STRUCTURE SIMULATIONS OF TWIN-ARGININE SIGNAL PEPTIDES IN DIFFERENT ENVIRONMENTS

Miguel A. San-Miguel (1) , Colin Robinson (2) , Mark Rodger (3)

1 Department of Physical Chemistry
2 Department of Biological Sciences [Coventry]
3 Department of Chemistry

The twin-arginine translocation (Tat) system transports folded proteins across bacterial plasma membranes and the chloroplast thylakoid membrane. A twin arginine motif in the signal peptide sequence plays a key role in the signal process. In this article we report the results of molecular dynamics simulations on a typical E. coli RR-signal peptide and two mutant variants in both aqueous and trifluoroethanol (TFE) solutions. It has been found that the peptide switches between two distinct states: random coil in water and some helical content in TFE. Our simulations demonstrate that the wild-type peptide is considerably more flexible than either of the mutants in both the solvents investigated. The twin arginine motif was found to provide a nucleation point for the formation of an α-helix in water, but also appears to destabilise α-helices in other regions of the peptide when dissolved in TFE.

Mots clés: Physical Sciences

Miguel A. San-Miguel, Colin Robinson, Mark Rodger. SECONDARY STRUCTURE SIMULATIONS OF TWIN-ARGININE SIGNAL PEPTIDES IN DIFFERENT ENVIRONMENTS. Molecular Simulation, 2009, 35 (12-13), pp.1033-1042. ⟨10.1080/08927020902974063⟩. ⟨hal-00530453⟩