Phosphatidylkojibiosyl diglyceride. The covalently linked lipid constituent of the membrane lipoteichoic acid from Streptococcus faecalis (faecium) ATCC 9790

Abstract

Water-soluble [14C]glycerol-labeled lipoteichoic acid isolated from the membrane preparations of Streptococcus faecalis (faecium) ATCC 9790 released chloroform-soluble radioactivity upon mild acid hydrolysis. Chromatography of the radioactive, chloroform-extractable material revealed the presence of a very polar lipid (lipid I). Depending upon the conditions of acid hydrolysis, lipid I accounted for as much as 92% of the total 14C-labeled lipids released. More stringent conditions of acid hydrolysis reduced the amount of lipid I and increased the quantity of the other lipids. Lipid I on further mild acid hydrolysis yielded phosphatidylkojibiosyl diglyceride almost quantitively. The other lipids released from the lipoteichoic acid were kojibiosyl diglyceride, monoglucosyl diglyceride, monoglyceride, diglyceride, and phosphatidylmonoglucosyl diglyceride. These lipids are most likely the degradation products of phosphatidylkojibiosyl diglyceride because they are all simpler, structural derivatives of the phosphoglucolipid and they increase in concentration with increasing acid hydrolysis. These and other data demonstrate that the glycerol phosphate polymer of the membrane lipoteichoic acid of S. faecalis (faecium) ATCC 9790 is covalently linked through a phosphodiester bond to phosphatidylkojibiosyl diglyceride.