Subunit composition of goblet-shaped particles from the cell wall of Flexibacter polymorphus

Submicroscopic goblet-shaped particles ( goblets ) were released from the cell envelope of the marine gliding bacterium Flexibacter polymorphus when treated with the nonionic detergent Triton X-100 followed by sonication. The goblets were purified by cesium chloride density gradient centrifugation and exhibited an equilibrium buoyant density of 1.30 g/mL at 23 degrees C. They were composed of protein and a small amount of carbohydrate (approximately 3.4% by weight). Aqueous suspensions exhibited an absorption maximum in the ultraviolet at a wavelength of 276 nm and a smaller shoulder at 281 nm. Phospholipids were not detected in purified preparations of goblets , though they are known to be prominent constituents of the intact membranes of this microbe. Polyacrylamide gel electrophoresis of goblets solubilized in sodium dodecyl sulfate and 2-mercaptoethanol indicated four major polypeptide components ranging in molecular weight from 13 000 to 80 000. This number of different protein subunits corroborates earlier ultrastructural observations indicating a multisubunit composition.