Fig. 6
Systematic reduction of the membrane activity of melittin in peptides with conserved double-stranded DNA (dsDNA)-binding activity corresponds with a recovery of TLR9-activating ability. a Small-angle X-ray scattering (SAXS) spectra from PS/PE = 20/80 model membranes incubated with melittin, AR23, RV23, and MM1 at P/L = 1/2. Melittin, AR23, and RV23 induce Pn3m cubic phases in model membranes, while MM1 does not induce appreciable changes compared to controls (Supplementary Figure 7). Correlation peaks corresponding to assigned reflections for the Pn3m cubic phases are labeled for melittin, AR23, and RV23. b SAXS spectra corresponding to the structures of melittin-, AR23-, RV23-, and MM1-DNA complexes. The melittin-DNA SAXS data are reproduced here from Fig. 1 for ease of comparison. Higher-order reflections for the AR23 and RV23 square lattices are labeled. AR23 and RV23 form square columnar lattices with dsDNA (similar to melittin and LL37), while MM1 forms a disordered columnar arrangement. c The absolute value of average negative Gaussian curvature (NGC) is calculated from the lattice parameter (a) of the cubic phases measured in a. Compared to melittin, AR23 and RV23 induce decreasing amounts of NGC in membranes, while MM1 does not induce NGC at all. d Measured TLR9-specific interferon (IFN)-ɑ production (pg mL−1) from human pDCs induced by AMP-dsDNA complexes. Systematic reduction of NGC-inducing ability in melittin-related peptides AR23 and RV23 (b) correlate with a recovery in ability to induce IFN-ɑ from pDCs. MM1 is unable to induce NGC or IFN-ɑ production from pDCs. Error bars denote s.e.m.
