Figure 5

Folding of P0ct_pept. (a) SRCD data show that P0ct_pept only displays folding with negatively charged SUVs. The most notable spectrum is the DMPC:DMPG (1:1) spectrum, which does not resemble classical helical content, nor β-sheets. (b) The effect of TFE and detergents on the conformation of P0ct_pept. While P0ct_pept only displays marginal folding with DPC, SDS induces an even higher secondary structure gain than 70% TFE, indicating the major importance of electrostatics in the folding of P0ct_pept. (c) OCD data of P0ct_pept in DMPC and DMPC:DMPG (1:1). Isotropic spectra are shown for reference. The DMPC OCD data is weak, typical for an aggregated sample, while also showing traces of helical content. The DMPC:DMPG (1:1) data displays clear folding and a more perpendicular orientation within the membrane. A simple cartoon has been drawn for clarity for both OCD datasets. Colors match the shown data. (d) Superposition of five predicted structures of P0ct_pept reveal the N-terminus likely to be disordered, followed by a kinking Pro (black asterisk), and a helical C-terminal segment. (e) Helical wheel projections of the basic N-terminal half (left) and the hydrophobic half (right) of P0ct_pept. The residues are colored based on chemical properties with matched indications in the peptide sequence (down). The underlined segments are shown in the projections. The potentially helix-breaking Pro has been indicated with an asterisk.