title: Identification of steroleosin in oil bodies of pine megagametophytes.
abstract: Three classes of integral proteins termed oleosin, caleosin and steroleosin have been identified in seed oil bodies of diverse angiosperm species. Recently, two oleosin isoforms and one caleosin were identified in megagametophyte oil bodies of pine (Pinus massoniana), a representative gymnosperm species. In this study, a putative steroleosin of approximately 41 kDa was observed in isolated oil bodies of pine megagametophytes, and its corresponding cDNA fragment was obtained by PCR cloning and further confirmed by mass spectrometric analysis. Phylogenetic tree analysis showed that pine steroleosin was evolutionarily more closely-related to steroleosin-B than steroleosin-A found in angiosperm seed oil bodies. As expected, artificial oil bodies constituted with recombinant steroleosin over-expressed in Escherichia coli were less stable and larger than native pine oil bodies. Filipin staining of artificial oil bodies sheltered by recombinant steroleosin with or without its sterol binding domain showed that the sterol binding domain was responsible for the sterol binding capability of steroleosin. Sterol-coupling dehydrogenase activity was demonstrated in artificial oil bodies constituted with recombinant steroleosin as well as in purified pine oil bodies.
authors.affiliation: Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan.
authors.forename: Buntora
authors.initials: B
authors.lastname: Pasaribu
authors.affiliation: Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan.
authors.forename: Tse-Yu
authors.initials: TY
authors.lastname: Chung
authors.affiliation: Taiwan Coral Research Center, National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan; Institute of Marine Biotechnology, National Dong-Hwa University, Pingtung 944, Taiwan.
authors.forename: Chii-Shiarng
authors.initials: CS
authors.lastname: Chen
authors.affiliation: Taiwan Coral Research Center, National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan; Institute of Marine Biotechnology, National Dong-Hwa University, Pingtung 944, Taiwan. Electronic address: villy@nmmba.gov.tw.
authors.forename: Pei-Luen
authors.initials: PL
authors.lastname: Jiang
authors.affiliation: Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan. Electronic address: TCTZEN@dragon.nchu.edu.tw.
authors.forename: Jason T C
authors.initials: JTC
authors.lastname: Tzen
mesh_terms: D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D066292:Lipid Droplets / Q000378:metabolism*; D056771:Ovule / Q000235:genetics / Q000378:metabolism; D028223:Pinus / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains
chemical_list: D002135:Calcium-Binding Proteins; D010940:Plant Proteins; C402836:caleosin protein, Sesamum indicum; C079355:oleosin protein, Pinus longaeva
keywords: Gymnosperm; Megagametophyte; Oil body; Pine; Steroleosin