Bacteria lacking lipopolysaccharides

Gram-positive bacteria lack the lipopolysaccharide layer encasing the cell, and therefore do not require the OM receptors such as FepA or FhuA to transport their siderophores into the cell (Figure Passage via diffusion is possible through the thick but porous peptidoglycan... 

Finally an intriguing aspect of H. influenzae infections warrants mention. These bacteria express a lipopolysaccharide whose exposed surface is decorated with phosphorylcholine. As described in Chapter 1, phosphorylcholine is a building block of phosphatidylcholine, a major membrane lipid of eukaryotic cells. However, most bacteria lack phosphatidylcholine and thus H. influenzae has to rely on host cell lipids to obtain phosphorylcholine. The transfer of phosphorylcholine from the host to the bacterial cell surface is an adaptative process that allows the pathogen to mimic characteristics of host cells and to become more resistant to host immune responses. Another astonishing case of "lipid mimicry" has been reported for H. influenzae. A particular strain of nontypable H. influenzae seemed to express a ganglioside GMl-like structure that has been suspected as a generator of anti-GMl antibodies responsible for an axonal Guillain-Barre syndrome. ... 

Polysaccharide moiety. The polysaccharide portion of lipopolysaccharide is known to be important in the virulence of many bacteria. Strains lacking polysaccharide side chains (rough strains) are invariably less virulent than those containing such structures. 

Vinogradov E, Egbosimba EE, Perry MB et al (2001) Structural analysis of the carbohydrate components of the outer membrane of the lipopolysaccharide-lacking cellulolytic ruminal bacterium Fibrobacter succinogenes S85. Eur J Biochem 268 3566-3576 Vogels G, Hoppe WF, Stumm CK (1980) Association of methanogenic bacteria with rumen dliates. Appl Environ Microbiol 40 608-612... 

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