title: Oleosin is bifunctional enzyme that has both monoacylglycerol acyltransferase and phospholipase activities.
abstract: In plants, fatty oils are generally stored in spherical intracellular organelles referred to as oleosomes that are covered by proteins such as oleosin. Seeds with high oil content have more oleosin than those with low oil content. However, the exact role of oleosin in oil accumulation is thus far unclear. Here, we report the isolation of a catalytically active 14 S multiprotein complex capable of acylating monoacylglycerol from the microsomal membranes of developing peanut cotyledons. Microsomal membranes from immature peanut seeds were solubilized using 8 m urea and 10 mm CHAPS. Using two-dimensional gel electrophoresis and mass spectrometry, we identified 27 proteins in the 14 S complex. The major proteins present in the 14 S complex are conarachin, the major allergen Ara h 1, and other seed storage proteins. We identified oleosin 3 as a part of the 14 S complex, which is capable of acylating monoacylglycerol. The recombinant OLE3 microsomes from Saccharomyces cerevisiae have been shown to have both a monoacylglycerol acyltransferase and a phospholipase A(2) activity. Overexpression of the oleosin 3 (OLE3) gene in S. cerevisiae resulted in an increased accumulation of diacylglycerols and triacylglycerols and decreased phospholipids. These findings provide a direct role for a structural protein (OLE3) in the biosynthesis and mobilization of plant oils.
authors: Department of Biochemistry, Indian Institute of Science, Bangalore 560012.
authors: Velayoudame
authors: V
authors: Parthibane
authors: Sona
authors: S
authors: Rajakumari
authors: Varadarajan
authors: V
authors: Venkateshwari
authors: Ramachandiran
authors: R
authors: Iyappan
authors: Ram
authors: R
authors: Rajasekharan
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D010367:Arachis / Q000201:enzymology* / Q000235:genetics; D008861:Microsomes / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D010740:Phospholipases / Q000235:genetics / Q000378:metabolism*; D010938:Plant Oils / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics
chemical_list: D009097:Multienzyme Complexes; D010938:Plant Oils; D010940:Plant Proteins; D011994:Recombinant Proteins; D000217:Acyltransferases; C021802:2-acylglycerol O-acyltransferase; D010740:Phospholipases