A bacterial light response reveals an orphan desaturase for human plasmalogen synthesis

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Science  04 Oct 2019:
Vol. 366, Issue 6461, pp. 128-132
DOI: 10.1126/science.aay1436

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Distant cousin helps spot animal enzyme

In addition to forming the membranes that enclose cells, lipids are important signaling molecules. Plasmalogens, which contain a vinyl ether linkage, are an abundant group of lipids in animals. How these lipids are synthesized from precursors with an alkyl ether linkage has been a mystery. Gallego-García et al. found an enzyme, CarF, in the social bacterium Myxococcus xanthus that produces plasmalogens used in a signaling pathway for singlet oxygen, a marker of photooxidative stress. They then showed that the animal homolog could catalyze the final step in plasmalogen synthesis in bacterial and human cells, thus resolving a source for plasmalogens in animals.

Science, this issue p. 128


Plasmalogens are glycerophospholipids with a hallmark sn-1 vinyl ether bond. These lipids are found in animals and some bacteria and have proposed membrane organization, signaling, and antioxidant roles. We discovered the plasmanylethanolamine desaturase activity that is essential for vinyl ether bond formation in a bacterial enzyme, CarF, which is a homolog of the human enzyme TMEM189. CarF mediates light-induced carotenogenesis in Myxococcus xanthus, and plasmalogens participate in sensing photooxidative stress through singlet oxygen. TMEM189 and other animal homologs could functionally replace CarF in M. xanthus, and knockout of TMEM189 in a human cell line eliminated plasmalogens. Discovery of the human plasmanylethanolamine desaturase will spur further study of plasmalogen biogenesis, functions, and roles in disease.

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