Conformational study of signal peptides of the LamB protein

A molecular mechanics study of a portion of the signal peptide of LamB protein, a mutant and two revertants, has been carried out. The peptides studied are: (I) Leu-Pro-Leu-Ala-Val-Ala-Val-Ala-Ala-Gly-Val for the wild type signal peptide; a mutant which shows no export capability (II), Leu-Pro-Val-Ala-Ala-Gly-Val; and two revertants with replacements of Pro by Leu (III), and Gly by Cys (IV) respectively. The results found are in agreement with the experimental data available; the aim of this work being to provide evidence of conformational features necessary along the export mechanisms. The present study suggests that both an alpha helix formation capability and a certain hydrophobicity of the peptide chain are the characteristics required for export competence.