Ether lipids synthesis pathways

Figure 24-4. Biosynthesis of ether lipids, including plasmalogens, and platelet-activating factor (PAF). In the de novo pathway for PAF synthesis, acetyl-CoA is incorporated at stage, avoiding the last two steps in the pathway shown here.

The question then arises by what pathways are archaeal ether lipids biosynthesized and how were these pathways selected rather than those used by all other organisms for acyl ester lipid synthesis The available information on lipid biosynthesis in archaea is based largely, with a few exceptions, on labelling studies with whole cells (see previous reviews [4,5,9,10,13,15,85]). Biosynthetic pathways for archaeol, caldarchaeol and their complex lipid derivatives will now be discussed. 

The total amount of porphyrins that accumulate in diphenyl ether-treated tissues is considerably higher than that which accumulates in untreated tissues (fiZ). Therefore, these herbicides appear to increase carbon flow into this pathway. Heme is known to feedback inhibit this pathway and PPIX is required for heme synthesis (9). Feeding heme to diphenyl ether-treated plant cells reduces the amount of porphyrin-caused lipid peroxidation of cell homogenates as measured by oxygen consumption (Ifl). 

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