Lactam-Stapled Cell-Penetrating Peptides: Cell Uptake and Membrane Binding Properties.

Stapling of side chains to stabilize an α-helical structure has been generally associated with an increased uptake of CPPs. Here, we compare four amphiphilic stapled peptides with their linear counterparts in terms of their membrane binding and conformational features in order to correlate these with uptake efficiency and toxicological effects. The impact of lactam stapling was found to vary strongly with regard to the different aspects of peptide-membrane interactions.

Membrane permeation of arginine-rich cell-penetrating peptides independent of transmembrane potential as a function of lipid composition and membrane fluidity.

Cell-penetrating peptides (CPPs) are prominent delivery vehicles to confer cellular entry of (bio-) macromolecules. Internalization efficiency and uptake mechanism depend, next to the type of CPP and cargo, also on cell type. Direct penetration of the plasma membrane is the preferred route of entry as this circumvents endolysosomal sequestration.

Folding and self-assembly of the TatA translocation pore based on a charge zipper mechanism.

We propose a concept for the folding and self-assembly of the pore-forming TatA complex from the Twin-arginine translocase and of other membrane proteins based on electrostatic "charge zippers." Each subunit of TatA consists of a transmembrane segment, an amphiphilic helix (APH), and a C-terminal densely charged region (DCR). The sequence of charges in the DCR is complementary to the charge pattern on the APH, suggesting that the protein can be "zipped up" by a ladder of seven salt bridges.

Structure analysis of the membrane-bound PhoD signal peptide of the Tat translocase shows an N-terminal amphiphilic helix.

Tat signal peptides provide the key signature for proteins that get exported by the bacterial twin arginine translocase. We have characterized the structure of the PhoD signal peptide from Bacillus subtilis in suitable membrane-mimicking environments. High-resolution ¹³C/¹⁵N NMR analysis in detergent micelles revealed a helical stretch in the signal peptide between positions 5 and 15, in good agreement with secondary structure prediction and circular dichroism results.