Protein and lipid composition analysis of oil bodies from two Brassica napus cultivars

Oil bodies were purified from mature seed of two Brassica napus crop cultivars, Reston and Westar. Purified oil body proteins were subjected to both 2-DE followed by LC-MS/MS and multidimensional protein identification technology. Besides previously known oil body proteins oleosin, putative embryo specific protein ATS1, (similar to caleosin), and 11-beta-hydroxysteroid dehydrogenase-like protein (steroleosin), several new proteins were identified in this study. One of the identified proteins, a short chain dehydrogenase/reductase, is similar to a triacylglycerol-associated factor from narrow-leafed lupin while the other, a protein annotated as a myrosinase associated protein, shows high similarity to the lipase/hydrolase family of enzymes with GDSL-motifs. These similarities suggest these two proteins could be involved in oil body degradation. Detailed analysis of the two other oil body components, polar lipids (lipid monolayer) and neutral lipids (triacylglycerol matrix) was also performed. Major differences were observed in the fatty acid composition of polar lipid fractions between the two B. napus cultivars. Neutral lipid composition confirmed erucic acid and oleic acid accumulation in Reston and Westar seed oil, respectively.