Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/1995
Publication Date: N/A
Technical Abstract: Acetyl-CoA carboxylase (ACCase) catalyzes the ATP dependent carboxylation of acetyl-CoA to form malonyl-CoA and is the first committed step in fatty acid biosynthesis. ACCases are either multifunctional polypeptides encoded by a single nuclear gene (eukaryotic-types) or, are a complex of separable polypeptides each encoded by a different gene (prokaryotic-types). In soybean we have characterized two >14 kb nuclear-encoded ACCase genes (ACCase-A and B). ACCase-A is encoded by 6789 nucleotides in 31 exons. Compared to ACCase-A, ACCase-B is missing 849 bp of 3' coding sequence. The coding sequences for ACCase-A and B are 95% and 99% homologous at the base and amino acid levels, respectively. Thus far, sequence data from neither gene has indicated the presence of a chloroplast transit peptide. Our isolation of two different cDNAs from a soybean leaf library suggests that both ACCase genes are expressed. A 330-bp PCR fragment synthesized from soybean chloroplast DNA showed >85% sequence homology to the carboxybiotin binding domain of the accD gene which encodes a subunit of the prokaryotic-type ACCase. We are using DNA probes from our cloned ACCases to determine the pattern of ACCase transcription during soybean seed development.