Lipid-destabilising properties of a peptide with structural plasticity

The Chameleon peptide (Cham) is a peptide designed from two regions of the GB1 protein, one folded as an α-helix and the other as a β structure. Depending on the environment, the Cham peptide adopts an α or a β conformation when inserted in different locations of GB1. This environment dependence is also observed for tilted peptides. These short protein fragments, able to destabilise organised system, are mainly folded in β structure in water and in α helix in a hydrophobic environment, like the lipid bilayer. In this paper, we tested whether the Cham peptide can be qualified as a tilted peptide. For this, we have compared the properties of Cham peptide (hydrophobicity, destabilising properties, conformation) to those of tilted peptides. The results suggest that Cham is a tilted peptide. Our study, together the presence of tilted fragments in transconformational proteins, suggests a relationship between tilted peptides and structural lability.