Membrane-derived oligosaccharide

Circles represent polar head groups of phospholipids. MDO, membrane-derived oligosaccharides KDO, 3-deoxy-manno-octulosonic acid (structures for KDO and heptose are in Fig. 4-15). From Raetz and Dowhan.587... 

Functioning in a somewhat different way in E. coli are 6- to 12-residue periplasmic membrane-derived oligosaccharides. These are p-1,2- and P 1,6-linked glucans covalently linked to sn-l-phospho-glycerol, phosphoethanolamine, or succinate (see Fig. 8-28).b e/f They accumulate in the periplasm when cells are placed in a medium of low osmolarity. 

S ATP + 1,2-diacyl-sn-glycerol <2, 3> (<2>, the enzyme functions to recycle diacylglycerol which is generated largely as a by-product of membrane-derived oligosaccharide biosynthesis [2] <3>, the enzyme may regulate the intracellular concentration of diacylglycerol [3]) (Reversibility <2, 3> [2, 3]) [2, 3]... 

Studies with mutant strains of E. coli have demonstrated that there is a connection between the turnover of membrane phospholipids and the synthesis of the so-called membrane-derived oligosaccharides , which are D-gluco-oligo-saccharides variously substituted with sn-glycerol phosphate, ethanolamine phosphate, and succinate on the outer envelope of the cell. The glycerol phosphate residues of these oligosaccharides appear to be donated by phosphatidyl-glycerol or the lipid cardiolipin or both. 

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