Lipoarabinomannan mycobacterial cell wall

The mycobacterial cell wall, discussed in Chapter 8, contains mycolic acids bound covalently at the nonreducing ends of arabinogalac-tans that are attached to the inner peptidoglycan layer,e as well as phosphatidylinositol-anchored lipoarabinomannans. Other unusual lipids that are also present and account for some of the difficulty of treatment with antibiotics include esters of mycocerosic acid with long-chain diols known as phenolphthiocerols and phthiocerols.f/fg... 

Retrosynthesis of octaarabinose 417. A component of lipoarabinomannan in mycobacterial cell wall... 

The mycobacterial cell wall contains the essential lipoglycan structures lipoarabinomannan, lipomannan, and phosphatidyl-my6>-inositol-mannosides (PIMs) [262]. These molecules are attached to the cytoplasmic membrane and extend through the cell wall into the extracellular environment (O Fig. 1). PIMs, LMs, and LAMs are attached to the cytoplasmic membrane by a conserved anchor, which consists of an sn-glycero-3-phospho-(l-D-my6>-inositol), with a single cx-D-Man/> linked at C2 of the my6>-inositol (O Fig. 19c). The mannan core is attached to C6 of the my6>-inositol unit. There are four potential sites of fatty acid attachment on the anchor both free hydroxyls of the glycerol unit, C6 of the Man/ linked to C2 of my6>-inositol and C3 of the my6>-inositol. The fatty acids are most commonly palmitic and tuberculostearic (10-methyl-octadecanoic) acids, and less frequently, stearic acid. Other fatty acids are seen in... 

Figure 16. A chemical model of the mycobacterial cell wall. The two major components are the mycolyl arabinogalactan-peptidoglycan complex and the lipoarabinomannan/lipomannan. The amount and exact chemical nature of the surface glycolipids are species- and/or strain-specific.

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