Molecular evidence of a unique lipoamide dehydrogenase in plastids: analysis of plastidic lipoamide dehydrogenase from Arabidopsis thaliana

Lipoamide dehydrogenase is a subunit of the alpha -ketoacid dehydrogenases and the glycine decarboxylase complex in mitochondria, and the pyruvate deh ydrogenase complex in plastids. We report here the unexpected finding of tw o plastidic isoforms of lipoamide dehydrogenase from Arabidopsis thaliana t hat are different from the mitochondrial form of the enzyme. The cDNA clone s were confirmed by sequence alignment analysis and their location verified by chloroplast import assay. They are single cop! genes that appear to be expressed in parallel in different tissues with highest level in developing siliques, Phylogenetic analysis gives further exemplary evidence for the p lastidic evolution derived from cyanobacteria. (C) 2000 Federation of Europ ean Biochemical Societies, Published by Elsevier Science B.V. All rights re served.