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The M2 protein is a multifunctional protein, which plays several roles in the replication cycle of the influenza A virus. Here we focus on its ability to promote budding of the mature virus from the cell surface. Using high-resolution small-angle X-ray scattering we show that M2 can restructure lipid membranes into bicontinuous cubic phases which are rich in negative Gaussian curvature (NGC). The active generation of negative Gaussian membrane curvature by M2 is essential to influenza virus budding. M2 has been observed to colocalize with the region of high NGC at the neck of a bud. The structural requirements for scission are even more stringent than those for budding, as the neck must be considerably smaller than the virus during 'pinch off'. Consistent with this, the amount of NGC in the induced cubic phases suggests that M2 proteins can generate high curvatures comparable to those on a neck with size 10× smaller than a spherical influenza virus. Similar experiments on variant proteins containing different M2 domains show that the cytoplasmic amphipathic helix is necessary and sufficient for NGC generation. Mutations to the helix which reduce its amphiphilicity and are known to diminish budding attenuated NGC generation. An M2 construct comprising the membrane interactive domains, the transmembrane helix and the cytoplasmic helix, displayed enhanced ability to generate NGC, suggesting that other domains cooperatively promote membrane curvature. These studies establish the importance of M2-induced NGC during budding and suggest that antagonizing this curvature is a viable anti-influenza strategy.

One member of a prototypical class of antimicrobial oligomers is used for studying pore formation in cardiolipin-rich membranes and both vesicle dye-leakage assays and small-angle X-ray scattering are used for studying bilayer remodeling. The results have shown that the presence of negative intrinsic curvature lipids is necessary for pore formation by this class of molecules.

The structures made by self-assembly of model membrane vesicles and members of a prototypical class of synthetic antimicrobial oligomers (AMOs) were examined by using synchrotron small-angle X-ray scattering (SAXS). The findings indicate that the ability of AMOs to restructure membranes is critically dependent on the concentration of negative-curvature lipids in a given membrane.

The synergistic roles of anionic and cationic template components in biomineralization of CdS nanorods are identified using self-assembled DNA-membrane complexes. DNA is highly anionic and condenses the Cd(super 2+) ions, while the cationic membrane modulates the concentration of condensed Cd(super 2+) ions to control the final CdS nanorod dimensions.

Crystallographic control in biomineralized inorganic nanostructures was achieved by employing a form of molecular imprinting using a synthetic, biomolecular template comprised of anionic and cationic components. The use of strong electrostatic interactions in this context has the potential to lead to new possibilities in supramolecular self-assembly and nanocrystal engineering.

It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers. [ABSTRACT FROM AUTHOR]

Complexes of anionic DNA and citionic liposomes self-assemble into a multilamellar structure where two-dimensional lipid sheets confine a periodic one-dimensional lattice of parallel. DNA chains, between which Cd2+ ions can condense, and be subsequently reacted with H2S to form CdS nanorods. In this work, we identify the synergistic roles of the anionic and cationic components within the DNA-membrane template; DNA is highly anionic and condenses the Cd2+ ions, while the cationic membrane modulates the concentration of condensed the Cd2+ ions to control the final CdS nanorod dimensions. Due to the strong electrostatic interactions between the DNA sugar-phosphate backbone and the Cd2+ ions, crystal-lographic control of CdS nanostructures is possible using these simple DNA-membrane templates, which we demonstrate using nanobeam electron diffraction experiments on individual templated CdS nanorods. [ABSTRACT FROM AUTHOR]

It is empirically known that anionic polyelectrolytes present in cystic fibrosis (CF) airways due to bacterial infection significantly decrease the activity of cationic antimicrobials via electrostatic binding. In this work, we use synchrotron small-angle X-ray scattering to investigate the interaction between tobramycin, an aminoglycoside antibiotic commonly administered to CF patients via inhalation, with DNA, which is found in high concentrations in the CF airway. We find that interactions between DNA and tobramycin are significantly modified by the presence of mixtures of amphiphilic molecules. We measure a hierarchy of self-assembled structures formed between tobramycin, DNA, and the amphiphile mixtures and show how interactions between these components can be controlled. Results indicate that mixtures of cationic and negative curvature amphiphiles optimized for DNA binding via charge matching and curvature matching can competitively displace bound tobramycin from DNA and thereby drastically suppress tobramycin-DNA binding and resultant antimicrobial inactivation. Growth inhibition assays confirm the increased activity of tobramycin in the presence of DNA with the addition of the amphiphiles. These results suggest that optimized cationic amphiphile solutions have the potential to enhance antimicrobial function in highly infected environments that contain increased concentrations of anionic inflammatory polymers.

A wide range of biomineralization and templating methods exist for organizing inorganic materials at a wide range of length-scales. Here, we show that crystallographic control of the inorganic nanostructures is possible using synthetic biomolecular templates comprised of anionic DNA and cationic membranes, which self-assemble into a multilamellar structure where a periodic one-dimensional (1D) lattice of parallel DNA chains is confined between stacked two-dimensional (2D) lipid sheets. We have organized Cd2+ ions within the interhelical pores between DNA strands and subsequently reacted them with H2S to form CdS nanorods of controllable widths and crystallographic orientation. The strong electrostatic interactions align the templated CdS (002) polar planes parallel to the negatively charged sugar-phosphate DNA backbone, which indicates that molecular details of the DNA molecule are imprinted onto the inorganic crystal structure. The resultant nanorods have (002) planes tilted by 60 degrees with respect to the rod axis, in contrast to all known II-VI semiconductor nanorods.