Phospholipid Tubelets

Abstract

A novel electron microscopy specimen protocol shows that the presumed phospholipid bilayer membrane ribbons that wind helically to form the cylinders known as "tubules" are actually flattened tubes. These flattened tubes are alternatively found with a helical twist about the tube's long axis or occasionally flat with no winding or twist. Flat, cylindrically wound and axially twisted segments are routinely found along a single tube's length, and at the helically wound and axially twisted segment junctions, the chiral sense of the structure often, but not always, changes chiral sense.

Negative-Stain Electron Microscopy of Inside-Out FtsZ Rings Reconstituted on Artificial Membrane Tubules Show Ribbons of Protofilaments

“…3 A). The EM showed a range of widths, with an average of 0.57 mm and lengths of 10-100 mm, which agrees with previously published data (23)(24)(25). These measurements were also consistent with the light microscopy images, in which the tubules were somewhat larger than the resolution.…”

“…The self-assembling DC8,9PC lipid formed a mixture of smooth tubules and helical structures, as previously reported (25,30). These were easily resolved by DIC light microscopy ( Fig.…”

“…In the study presented here, we developed another lipid tubule system to investigate Z ring substructure. The synthetic lipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3phosphocholine (DC8,9PC or DC 23 PC), which has a diacetylenic group halfway down each of its 23-carbon hydrocarbon chains, spontaneously forms hollow tubes 0.5 mm in diameter and 1-100 mm long (23)(24)(25). The diameter is larger than the 0.25 mm resolution of the light microscope, permitting observation of rings by fluorescence microscopy.…”

Supramolecular Structures Generated by a p‐tert‐Butylphenyl‐amide Derivative of Cholic Acid: From Vesicles to Molecular Tubes

“…Matsui and Gologan [27] have observed direct structural transformations between tubules and helical ribbons, the conversion helical ribbons → tubules being 10 times faster than the reverse conversion. Mishra et al [28] have observed that the presumed phospholipid bilayer membrane ribbons that wind helically to form tubules are actually flattened tubes. iv) Lee et al [29] have proposed, for a diacetylenic amine salt, that rolling up a bilayer lamellar structure also gives rise to tubes.…”

Self‐Assembled Cylindrical Lipid Tubules with a Birefringent Core

“…The rolling of lipid bilayer sheets into hollow cylindrical tubules has led to a number of novel nanostructured materials 1–3. It has been found that a number of synthetic lipids with modified head groups or acyl chains are able to self‐assemble into tubule structures in solution 4–15. The diameter of these self‐assembled tubules spans over a range from 10 nm to 1.0 μm, depending on the nature of the lipids and the conditions under which molecular self‐assembly occurs.…”