title: AtABCA9 transporter supplies fatty acids for lipid synthesis to the endoplasmic reticulum.
abstract: Fatty acids, the building blocks of biological lipids, are synthesized in plastids and then transported to the endoplasmic reticulum (ER) for assimilation into specific lipid classes. The mechanism of fatty acid transport from plastids to the ER has not been identified. Here we report that AtABCA9, an ABC transporter in Arabidopsis thaliana, mediates this transport. AtABCA9 was localized to the ER, and atabca9 null mutations reduced seed triacylglycerol (TAG) content by 35% compared with WT. Developing atabca9 seeds incorporated 35% less (14)C-oleoyl-CoA into TAG compared with WT seeds. Furthermore, overexpression of AtABCA9 enhanced TAG deposition by up to 40%. These data strongly support a role for AtABCA9 as a supplier of fatty acid substrates for TAG biosynthesis at the ER during the seed-filling stage. AtABCA9 may be a powerful tool for increasing lipid production in oilseeds.
authors.affiliation: Division of Molecular Life Sciences,  Pohang University of Science and Technology, Pohang 790-784,  Korea.
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Kim
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Yamaoka
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ono
authors.forename: Hanul
authors.initials: H
authors.lastname: Kim
authors.forename: Donghwan
authors.initials: D
authors.lastname: Shim
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Maeshima
authors.forename: Enrico
authors.initials: E
authors.lastname: Martinoia
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Cahoon
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nishida
authors.forename: Youngsook
authors.initials: Y
authors.lastname: Lee
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002498:Centrifugation; D017931:DNA Primers / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D008055:Lipids / Q000096:biosynthesis*; D012639:Seeds / Q000737:chemistry
chemical_list: D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D017931:DNA Primers; D005227:Fatty Acids; D008055:Lipids