C-terminal secretion signal of an Erwinia chrysanthemi protease secreted by a signal peptide-independent pathway: proton NMR and CD conformational studies in membrane-mimetic environments

Nicolas Wolff (1) , Jean-Marc Ghigo (2) , Philippe Delepelaire (2) , Cécile Wandersman (2) , Muriel Delepierre (1)

1 Résonance Magnétique Nucléaire
2 Génétique Moléculaire

The detailed structure of a 68-residue chimeric peptide encompassing the 56 last C-terminal residues of Erwinia chrysanthemi protease G has been investigated by using circular dichroism and NMR spectroscopies. The peptide which contains the secretion signal of PrtG was solubilized either in aqueous solvent, in trifluoroethanol (TFE)/H2O mixtures, or in dodecyl beta-D-maltoside detergent. The peptide helical content increases upon TFE and detergent additions. A stable conformation is reached at 40% TFE (v:v) and at a micelle to peptide ratio higher than 1. The 1H NMR spectrum has been assigned in TFE/H2O, 2:1 (v:v), and it is shown that residues 26-29 and 50-62 form a relatively stable helix although a conformational equilibrium between a helix and probably a more random structure is observed throughout fragment 13-63. Comparison of the CterG conformation with results obtained by deletion approach could lead to the hypothesis that the C-terminal secretion signal is composed of an alpha-helix located close to the essential C-terminal tetrapeptide D65VIV.

Domaines: Sciences du Vivant [q-bio]

Nicolas Wolff, Jean-Marc Ghigo, Philippe Delepelaire, Cécile Wandersman, Muriel Delepierre. C-terminal secretion signal of an Erwinia chrysanthemi protease secreted by a signal peptide-independent pathway: proton NMR and CD conformational studies in membrane-mimetic environments. Biochemistry, 1994, 33 (22), pp.6792-6801. ⟨pasteur-00389611⟩