5-Octadecenoic acid: evidence for a novel type of fatty acid modification in schistosomes.
The lipid metabolism of schistosomes is characterized by several intriguing adaptations to a parasitic way of living. The surface of the parasite consists of two closely apposed phospholipid bilayers, a structure unique to blood flukes. Schistosomes do not synthesize fatty acids de novo, but are able to modify fatty acids, which they obtain from the host, by chain elongation. Here we present evidence that schistosomes are capable of another type of fatty acid modification, resulting in the formation of 5-octadecenoic acid [C18:1(5)]. This highly unusual fatty acid, which is absent in the blood of the host, was shown to be almost exclusively located in the outer membrane complex of the schistosome. Within these membranes, it was almost exclusively present in one molecular phospholipid species, 1-palmitoyl-2,5-octadecenoyl phosphatidylcholine [C16:0-18:1(5)PtdCho]. Apart from dipalmitoyl phosphatidylcholine, this was the most abundant phosphatidylcholine species in the outer membrane complex. The specific synthesis by the schistosome of C18:1(5) and the highly specific localization of this fatty acid to the tegumental membranes suggest an important tegument-mediated role for this lipid.
Laboratory of Veterinary Biochemistry and Institute of Biomembranes, Utrecht University, P.O. Box 80176, 3508 TD Utrecht, The Netherlands.
J F
JF
Brouwers
C
C
Versluis
L M
LM
van Golde
A G
AG
Tielens
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D007536:Isomerism; D019301:Oleic Acid; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000737:chemistry / Q000378:metabolism*; D018629:Spectrometry, Mass, Secondary Ion; D013229:Stearic Acids / Q000032:analysis / Q000378:metabolism*
C114874:5-octadecenoic acid; D010743:Phospholipids; D013229:Stearic Acids; D019301:Oleic Acid