Figure 3.

(A–F) Membrane structural transformations of DMPC bilayer patches induced by the positively charged AMPs aurein-1.1 (A), citropin-1.1 (B), magainin-1 (C), dermaseptin-1 (D), indolicidin (E), and HBD-1 (F). Bilayer patches were first imaged in the absence of peptide (A1, B1, C1, etc.) and then monitored through the course of successive peptide concentrations (increasing from left to right). (A) Increasing concentrations of aurein-1.1 revealed edge instability and a porated membrane (A2). Micrograph (A3) is from a separate experiment showcasing worm-like micelle formation by 3 μM aurein-1.1. (B) Citropin-1.1 exhibited a similar response to aurein-1.1, displaying edge instability and a porated membrane (B2), with worm-like micelle formation (B3) occurring by 3 μM. The concentration responses of magainin-1, dermaseptin-1, and indolicidin were similar, as the onset of micellization (C3, D3, and E3) occurred in the same range below 0.5 μM. The bilayer patch monitored through images (E1) and (E2) was inadvertently smeared, and a nearby patch (E3) on the substrate was chosen to obtain a high-resolution image of worm-like micelles induced by indolicidin. To better reveal the self-assembled structures, the dashed box in (E3) indicates a zoomed-in region shown in the inset (data scaled to a 5 nm range). (F) Although bilayer edge instability was observed at 0.3 μM HBD-1 (F2), a significantly higher amount of peptide was needed to observe detergent behavior (F3). All images were obtained at 30°C. White scale bars are 500 nm unless otherwise indicated. To see this figure in color, go online.