Phosphatidylinositol mannosides

Hoppe, H.C., de Wet, B.J., Cywes, C., Daffe, M., and Ehlers, M.R., 1997, Identification of phosphatidylinositol mannoside as a mycobacterial adhesin mediating both direct and opsonic binding to non phagocytic mammalian cells. Infect. Immun. 65 3896—3905. 

Phosphatidylinositol Mannoside, Lipomannan, Lipoarabinomannan, and Arabinomannan Structure 383... 

Biosynthesis of the Phosphatidylinositol Containing Phosphatidylinositol Mannosides, Lipomannans, and Lipoarabinomannans 395... 

In contrast with the previous reports, no phosphatidylinositol mannosides could be detected (Sutcliffe and Shaw, 1993). The major phospholipids identified in P. freudenreichii were bis(phosphatidyl)glycerol, phosphatidyl-glycerol and phosphatidylinositol, with small contributions from phosphatid-ylethanolamine and lysophosphatidylinositol. The relative abundance of the two phosphatidylglycerol species is perfectly consistent with the taxonomic position of the propionibacteria among the Gram-positive eubacteria, especially their close relations with actinomycetes. 

Mannosides of phosphatidylinositol are important serologically active components of Mycobacterium tuberculosis. For the synthesis of the 2-O-mannosyl derivative (421), Stepanov et al. [291] treated the chiral prop-l-enyl ether (414) [and the corresponding racemic prop-l-enyl ether and racemic benzoate (415)] with the orthoesters (416) or (417) to give the disaccharide (418) [from chiral (414) and acetate (416)] in moderate yield. The disaccharide obtained from racemic (414) contained a high proportion of (418) as a result of asymmetric synthesis. Acidic hydrolysis of (418) gave in low yield (30%) the alcohol (419). 

Phosphatidylinositol is uncommon in bacteria and is found in a few Gram-positive species only. In actinomycetes and a few other bacteria mannosides of phosphatidylinositol may be present. Other glycerophospholipids such as phosphatidic acid and phosphatidylserine have a widespread occurrence in bacteria but only in small amounts. Both of these lipids play an important role as metabolic intermediates (Finnerty, 1978 Raetz, 1978). 

Discoside is another example of a glycolipid containing myo-inositol. It comes from the species Discodermia dis-soluta harvested in the Bahamas (Berry Island). Discoside is one of the few examples of a phosphatidylinositol a-mannoside (Barbieri et al., 2005). 

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