Membrane-Fusogen Distance Is Critical for Efficient Coiled-Coil-Peptide-Mediated Liposome Fusion.

We have developed a model system for membrane fusion that utilizes lipidated derivatives of a heterodimeric coiled-coil pair dubbed E (EIAALEK) and K (KIAALKE). In this system, peptides are conjugated to a lipid anchor via a poly(ethylene glycol) (PEG) spacer, and this contribution studies the influence of the PEG spacer length, coupled with the type of lipid anchor, on liposome-liposome fusion. The effects of these modifications on peptide secondary structure, their interactions with liposomes, and their ability to mediate fusion were studied using a variety of different content mixing experiments and CD spectroscopy.

Interplay between Lipid Interaction and Homo-coiling of Membrane-Tethered Coiled-Coil Peptides.

The designed coiled-coil-forming peptides E [(EIAALEK)3] and K [(KIAALKE)3] are known to trigger efficient membrane fusion when they are tethered to lipid vesicles in the form of lipopeptides. Knowledge of their secondary structure is a key element in understanding their role in membrane fusion. Special conditions can be found at the interface of the membrane, where the peptides are confined in close proximity to other peptide molecules as well as to the lipid interface.

Biomaterials for mRNA delivery.

Messenger RNA (mRNA) has recently emerged with remarkable potential as an effective alternative to DNA-based therapies because of several unique advantages. mRNA does not require nuclear entry for transfection activity and has a negligible chance of integrating into the host genome which excludes the possibility of potentially detrimental genomic alternations. Chemical modification of mRNA has further enhanced its stability and decreased its activation of innate immune responses.

Determination of oligomeric states of peptide complexes using thermal unfolding curves.

In their native form peptides are often found as oligomeric complexes, meaning they consist of more than one peptide chain. Coiled coils and helical bundles are common examples of such complexes. Their oligomeric state needs to be known precisely as this tremendously influences their biochemical and biophysical properties.

Library of random copolypeptides by solid phase synthesis.

Random copolypeptides are promising and versatile bioinspired macromolecules of minimal complexity for studying their interactions with both living and synthetic matter. They provide the opportunity to investigate the role of, for example, total net charge and hydrophobicity through simply changing the monomer composition, without considering the effect of specific sequences or secondary structure. However, synthesizing large libraries of these polymers so far was prohibited by the time-consuming preparation methods available (ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides and enzymatic polymerization of amino acids).

Membrane interactions of fusogenic coiled-coil peptides: implications for lipopeptide mediated vesicle fusion.

Fusion of lipid membranes is an important natural process for the intra- and intercellular exchange of molecules. However, little is known about the actual fusion mechanism at the molecular level. In this study we examine a system that models the key features of this process.

Coiled-coil peptide motifs as thermoresponsive valves for mesoporous silica nanoparticles.

Coiled-coil peptide motifs were used as thermo-responsive valves for mesoporous silica nanoparticles (MSNs). The controlled release of a model drug as a function of temperature was demonstrated.

Controlling the rate of coiled coil driven membrane fusion.

Sets of complementary lipidated coiled-coil forming peptides that fuse membrane fusion have been designed. The influence of the coiled-coil motif on the rate of liposome fusion was studied, by varying the number of heptad repeats. We found that an increased coiled-coil stability of complementary peptides translates into increased rates of membrane fusion of liposomes.