Functionalized Lipid Tubules as Tools for Helical Crystallization of Proteins

Abstract

Abstract:The development of functional supramolecular devices built by self-asscmbly of elementary molecules and with bioactive properties arouses considerable interest in the field of nanotechnology and new materials. Wc rcport hcrc thc formation of a new class of lipid tubules exhibiting both properties of molecular recognition and crystal forination for the protein streptavidin. These lipid tubules, made of biotin-containing dioctadecylamine molecules, are straight hollow cylinders with a constant diameter of 27 nm and variable length up to several micrometers. Thcy are unilamellar with an inner diameter of about 16 nm, as shown by cryoelectron Keywords helical structures * lipids * liposomes * self-assembly * tubule!; microscopy. Streptavidin binds to the biotinylated tubules and assembles spontaneously into ordered hclical arrays at the tube surface. These crystals exhibit regular order up to about 1.5 nm resolution. In addition, the helical streptavidin arrays act as functionalized supramolecular devices that bind a wide variety of biotinylated objects, as demonstrated here with proteins and liposomes.

Relationship between molecular structure and supramolecular morphology of DODA-EO2-biotin and related lipids

“…Ribbons formed by lipid 7 presented a wavy aspect and consisted of the juxtaposition of filamentous DOPC mixtures and by lipids 5 -8 was studied by TEM. When streptavidin was added in saturating conditions to tubes obtained at 4°C with 1:1, 1:4 and 1:10 DODA-EO 2 -biotin/DOPC solutions, ordered helical arrays of streptavidin were obtained, exhibiting the same structural characteristics as previously described (Ringler et al, 1997) (Fig. 9).…”

“…4). The lipid tubules were straight and had a constant diameter of about 27 nm and a length ranging from a few hundred nanometers up to several micrometers, as previously described (Ringler et al, 1997). The length- to-diameter ratio of the tubular aggregates ranged from 10 2 to 10 3 .…”

“…The binding of strepatvidin to lipid supramolecular structures formed with lipids 4-8 was carried out as previously described (Ringler et al, 1997). Negative staining was carried out with 1% uranyl acetate, pH 3.5.…”

“…We have recently reported that a biotinylated lipid molecule, called DODA-EO 2 -biotin, forms tubular lipid structures upon hydration, which act as a matrix for the formation of ordered helical arrays of streptavidin as well as for secondary macromolecular recognition reactions involving biotinylated structures (Ringler et al, 1997). In the present study, the supramolecular structures formed by the compounds obtained during the synthesis of DODA-EO 2 -biotin and of compounds structurally related to DODA-EO 2 -biotin were investigated by transmission electron microscopy, with the objective being to understand the relationship between molecular structure and supramolecular morphology.…”

“…We have recently described a new type of lipid tubule formed by the DODA-EO 2 -biotin molecule (Ringler et al, 1997). These molecules extend the field of supramolecular structures with tubular morphology by adding the property of molecular recognition for proteins.…”