THE GLYCOINOSITOL-PHOSPHOLIPIDS OF PHYTOMONAS

The Phytomonas spp. are trypanosomatid parasites of plants. A polar gl ycolipid fraction of a Phytomonas sp., isolated from the plant Euphorb ia characias and grown in culture, was fractionated into four major gl ycolipid species (Phy 1-4). The glycolipids were analysed by chemical and enzymic modifications, composition and methylation analyses, elect rospray mass spectrometry and microsequencing after HNO2 deamination a nd (NaBH4)-H-3 reduction. The water-soluble headgroup of the Phy2 glyc olipid was also analysed by H-1 NMR. All four glycolipids were shown t o be glycoinositol-phospholipids (GIPLs) with phosphatidylinositol (PI ) moieties containing the fully saturated alkylacylglycerol lipids 1-O -hexadecyl-2-O-palmitoylglycerol and 1-O-hexadecyl-2-O-stearoylgIycero l. The structures of the Phy 1-4 GIPLs are: Man alpha 1-2Man alpha 1-6 Man alpha 1-4GlcN alpha 1-6PI, Glc alpha 1-2(NH2CH2CH2-HPO4-) Man alph a 1-2Man alpha 1-6Man alpha 1-4GlcNal-6PI, Glc alpha 1-2(NH2CH2CH2-HPO 4-)Man alpha 1-2Man alpha 1-6Man alpha 1-4(NH2CH2CH2-HPO4-)GlcNc alpha 1-6PI and Glc alpha 1-2Glc alpha 1-2(NH2CH2CH2-HPO4-)Man alpha 1-2Man alpha 1-6Man alpha 1-4(NH2CH2CH2-HPO4-)GlcN alpha 1-6PI. The Phytomon as GIPLs represent a novel series of structures. This is the fist desc ription of the chemical structure of cell-surface molecules of this pl ant pathogen. The Phytomonas GIPLs are compared with those of other tr ypanosomatid parasites and are discussed with respect to trypanosomati d phylogenetic relationships.