Isolation of a gene encoding Arabidopsis membrane‐associated acyl‐CoA binding protein and immunolocalization of its gene product

• Published in: The Plant journal : for cell and molecular biology 1999-04, Vol.18 (2), p.205-214
• Main Authors: Chye, Mee‐Len, Huang, Bing‐Quan, Zee, Sze Yong
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - genetics; Base Sequence; Biological and medical sciences; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell biochemistry; Cell physiology; Diazepam Binding Inhibitor; DNA, Complementary; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes. Genome; Lipid Metabolism; Microscopy, Immunoelectron; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Plant physiology and development; Seeds - ultrastructure
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.1999.00443.x

Summary Until recently, only cytosolic acyl‐CoA binding proteins (ACBPs) have been characterized. The isolation of an Arabidopsis thaliana cDNA encoding a novel membrane‐associated ACBP that accumulates in developing seeds, designated ACBP1, has provided evidence for the existence of membrane‐associated forms of ACBPs ( Chye 1998, Plant Mol. Biol. 38, 827–838). We now report on the isolation of its corresponding gene from an A. thaliana Columbia genomic library using the ACBP1 cDNA as a hybridization probe. Nucleotide sequence analysis of Arabidopsis ACBP1 showed that its promoter lacks a TATA box, resembling the promoters of rat, Drosophila and human genes encoding cytosolic ACBP and suggesting that it is a housekeeping gene. We show by Western blot analysis that ACBP1 expression in developing seeds coincides with lipid deposition and that homologues of membrane‐associated ACBP1 exist in other plants. Using light microscopy, we show that ACBP1 is strongly expressed in the embryo at the cotyledons, hypocotyl, procambium of the axis and in most peripheral cells of the cotyledons and hypocotyl. Immunogold labelling localized ACBP1 to vesicles, to the plasma membrane especially at epidermal cells of heart, torpedo and cotyledonary stage embryos, and to the cell wall of the outer integument cells at the seed coat. Our results suggest that ACBP1 is involved in intermembrane lipid transport from the ER via vesicles to the plasma membrane where it could maintain a membrane‐associated acyl pool; its immunolocalization to the cell wall of outer integument cells at the seed coat suggests a role in cuticle and cutin formation.