Photopolymerization of polydiacetylene in hybrid liposomes:Effect of polymerization on stability and response to pathogenic bacterial toxins

Liposomes containing lipids and polydiacetylene (PDA) are hybrid systems encompassing both a fluid phospholipid membrane and a polymer scaffold (PDA). However, the biophysical role of PDA in such liposomes is not well understood. In this report, we studied the effects of photopolymerization of PDA on the stability of lipid-PDA liposomes, and their sensitivity to selected purified toxins and bacterial supernatants, using a fluorescence assay. Of the three different types of liposomes with variable lipid chain lengths that were chosen, the degree of polymerization had a significant impact on the long-term stability, and response, to external microbial exotoxins secreted by pathogenic bacteria, namely, Staphylococcus aureus and Pseudomonas aeruginosa. The degree of polymerization of TCDA played an important role in lipid-chain-length-dependent stabilization of lipid-PDA liposomes, as well as in their response to bacterial toxins of S. aureus and P. aeruginosa.</p

Functional supramolecules: Vesicles Head in White Direction

Synthetic vesicles with membranes made from amphiphiles that are fluorescence acceptors encapsulate donor molecules in their cores, and emit different proportions of red, blue and green light depending on pH. The balance of these coloured emissions at pH 9 results in white fluorescence

Structure function studies of the magnetite biomineralizing magnetosome associated protein MamC

Magnetotactic bacteria are Gram-negative bacteria that navigate along geomagnetic fields using the magnetosome, an organelle that consists of a membrane-enveloped magnetic nanoparticle. Magnetite formation and its properties are controlled by a specific set of proteins. MamC is a small magnetosome-membrane protein that is known to be active in iron biomineralization but its mechanism has yet to be clarified. Here, we studied the relationship between the MamC magnetite-interaction loop (MIL) structure and its magnetite interaction using an inert biomineralization protein-MamC chimera. Our determined structure shows an alpha-helical fold for MamC-MIL with highly charged surfaces. Additionally, the MamC-MIL induces the formation of larger magnetite crystals compared to protein-free and inert biomineralization protein control experiments. We suggest that the connection between the MamC-MIL structure and the protein’s charged surfaces is crucial for magnetite binding and thus for the size control of the magnetite nanoparticles