Bacterial Sphingolipids and Sulfonolipids

Abstract

The bacterial envelope is often composed by two membranes: the inner or cytoplasmic membrane and an outer membrane. The inner membrane consists of a lipid bilayer with phospholipids covering the inner and the outer leaflet. Although the outer membrane displays a bilayer structure as well, only the inner leaflet of the outer membrane is composed of phospholipids, whereas the outer leaflet is typically formed by lipid A-containing lipopolysaccharides in Gram-negative bacteria. However, some bacteria lack lipopolysaccharides and have sphingolipids in the outer leaflet of their outer membrane instead. Sphingolipids are considered to be typical eukaryotic membrane lipids, essential components of the plasma membrane, and are crucial for signaling and organization of lipid rafts in eukaryotes.