CHARACTERIZATION OF AN ACYL-COA-BINDING PROTEIN FROM ARABIDOPSIS-THALIANA

A cDNA clone was obtained from Arabidopsis thaliana that encodes a pro tein containing 92 amino acid residues with high sequence identity (57 %) to bovine acyl-CoA-binding protein (ACBP). The coding sequence of t his clone was expressed in Escherichia coli and the gene product (10.4 kDa) was purified. The recombinant A. thaliana ACBP (rAthACBP) was sh own to bind acyl-CoA esters and protect acyl-CoAs from degradation by microsomal acyl-hydrolases. Antibodies that were raised to rAthACBP re cognized the native Arabidopsis ACBP and also cross-reacted with a num ber of other plant ACBPs, including rapeseed (Brassica napus) ACBP. Th e pattern of expression and level of the gene product were examined in various tissues of Arabidopsis and Brassica using Western blotting. A . thaliana tissues contained between 3 and 143 mu g AthACBP g(-1) FW d epending on the tissue (0.4 to 14 nmol g(-1) FW). Developing B. napus seeds underwent a 12-fold increase in ACBP levels during seed maturati on (20 to 250 pg ACBP g(-1) FW); the highest concentration occurring n ear the peak of triacylglycerol accumulation (26 nmol g(-1) FW). (C) 1 996 Academic Press, Inc.