Surface-induced synthesis of new sulfonolipids in the gliding bacterium Cytophaga johnsonae

Abstract

Many simple gliding bacteria contain significant quantities of phosphate-free, sulfur-containing lipids (sulfonolipids; N-acylamino-3-hydroxyisoheptadecane-1-sulfonic acids, or N-acyl capnines) that recently were shown to function in the ability of Cytophaga johnsonae to migrate over solid surfaces. Reported here is the synthesis, by surface-grown Cytophaga johnsonae cells, of two additional sulfonolipids not present in cells grown in liquid media. These newly characterized sulfonolipids are more polar than the N-acylcapnines characteristic of liquid grown cells. Acid methanolysis of the sulfonolipids revealed that the aminosulfonate capnine was common to all, thus indicating that the chemical differences in the compounds resided in their N-fatty acyl groups, and not in the aminosulfonate moiety. Instead of the non-hydroxy and 3-hydroxy fatty acyl moieties present in sulfonolipids of liquid-grown cells, one new sulfonolipid contained a 2-hydroxy, branched C₁₅ fatty acid, while the other contained a 2,3-dihydroxy, isobranched C₁₆ fatty acid, as indicated by gas chromatographic and mass spectrometric analyses. Although the structure of sulfonolipids thus varies between surface- and liquid-grown cells, no difference was found between the total quantity of sulfonolipids present under either of these conditions. The surface-dependent synthesis of these more polar N-acyl-aminosulfonates ceased immediately when surface-grown populations were suspended in broth. The ability of Cytophaga johnsonae to synthesize these compounds in response to a solid surface may be significant in relation to the organism's ability to migrate over such surfaces; it is one of few instances where a physical interaction of the cell surface has been shown to influence the molecular composition of a prokaryote.