Bacterial glycolipids activators

The hydrophobic products were isolated by TLC and characterized by means of NMR, ESI-CID-MS/MS, and FAB-CID-MS/MS as lipophilic long-chain alkyl diethanol amines, which are shown in Figure 7. In the literature these unusual lipophilic amines were not detected as constituents of any bacterial cells. Although the mode of linkage in the whole glycolipid is not clear at this moment, we speculate that these lipophilic amines that commonly existent in the cytokine-inducing gly-colipids from E. hirae are essential moieties for the cytokine-inducing activity. 

Likewise, the A chains of other plant [42-44] and bacterial [45-47] hetero-dimeric toxins are responsible for toxicity. These toxins contain a single A chain moiety which, in each case, has catalytic activity and efficiently inactivates its intracellular target [44]. The A chain is only toxic to intact cells when combined with B chain. The function of the B chain is to bind the toxin to cell-surface receptors, in the case of ricin to appropriate surface glycoproteins or glycolipids. This is the essential first step in the transfer of ricin A chain into the cytosol, where ribosome inactivation occurs [48]. Additionally, the B chain is believed to have a second function during the intoxication process in which it facilitates the transfer of the A chain across a membrane into the cytoplasm [49]. Separated A and B chains are essentially non-toxic, the toxic A chain lacking the ability to bind to and enter cells in the absence of the B chain. The toxicity of ricin therefore results from three sequential steps (1) binding of the whole molecule to the cell surface via the B chain (2) penetration of at least the A chain into the cytosol, and (3) inhibition of protein synthesis caused by the interaction of the A chain with the 60 S ribosomal subunit. 

The phospholipid composition also is an important taxonomic indicator of the genus. Biochemical activity of the cell depends considerably on the association of some specific proteins with phospholipids. In bacterial membranes one major phospholipid, accounting for 50% or more of the total, is usually found (Salton and Owen, 1976). The major phospholipid class in propionibacteria is represented by glycolipids, which amount to about 40% of the total lipids in P. shermanii, with smaller amounts in P. freudenreichii and P. arabinosum (Shaw and Baddiley, 1968). The exact... 

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