Oxidation-responsive supramolecular hydrogels based on glucosamine derivatives with an aryl sulfide group.

Supramolecular hydrogels can be obtained via self-assembly of small molecules in aqueous environments. In this study, we describe the development of oxidation-responsive supramolecular hydrogels comprising glucosamine derivatives with an aryl sulfide group. We demonstrate that hydrogen peroxide can induce a gel-sol transition through the oxidation of the sulfide group to the corresponding sulfoxide. Furthermore, we show that this oxidation responsiveness can be extended to photo-responsiveness with the aid of a photosensitizer.

Design of supramolecular hybrid nanomaterials comprising peptide-based supramolecular nanofibers and in situ generated DNA nanoflowers through rolling circle amplification.

The artificial construction of multicomponent supramolecular materials comprising plural supramolecular architectures that are assembled orthogonally from their constituent molecules has attracted growing attention. Here, we describe the design and development of multicomponent supramolecular materials by combining peptide-based self-assembled fibrous nanostructures with globular DNA nanoflowers constructed by the rolling circle amplification reaction. The orthogonally constructed architectures were dissected by fluorescence imaging using the selective fluorescence staining procedures adapted to this study. The present, unique hybrid materials developed by taking advantage of each supramolecular architecture based on their peptide and DNA functions may offer distinct opportunities to explore their bioapplications as a soft matrix.

Physiological lipid composition is vital for homotypic ER membrane fusion mediated by the dynamin-related GTPase Sey1p.

Homotypic fusion of the endoplasmic reticulum (ER) is required for generating and maintaining the characteristic reticular ER membrane structures. This organelle membrane fusion process depends on the ER-bound dynamin-related GTPases, such as atlastins in animals and Sey1p in yeast. Here, to investigate whether specific lipid molecules facilitate GTPase-dependent ER membrane fusion directly, we comprehensively evaluated membrane docking and lipid mixing of reconstituted proteoliposomes bearing purified Sey1p and a set of ER-mimicking lipids, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, and ergosterol. Remarkably, we revealed that each specific lipid species contributed little to membrane docking mediated by Sey1p. Nevertheless, Sey1p-dependent lipid mixing was strongly reduced by omitting three major acidic lipids from the ER-mimicking set and, moreover, was entirely abolished by omitting either phosphatidylethanolamine or ergosterol. Our reconstitution studies thus established that physiological lipid composition is vital for lipid bilayer rearrangements in GTPase-mediated homotypic ER membrane fusion.