Cloning of cDNAs encoding isopropylmalate dehydrogenase from Arabidopsis thaliana and accumulation patterns of their transcripts.

Isopropylmalate dehydrogenase (IPMDH) is an enzyme in the leucine biosynthetic pathway. We isolated three IPMDH ORF sequences from Arabidopsis thaliana, and genes corresponding to these ORF sequences were designated AtIMD1, AtIMD2, and AtIMD3. Deduced amino acid sequences of the three genes contain a putative transit-peptide for plastidic localization. AtIMD1, AtIMD2, and AtIMD3 were able to complement a leu2 mutant of yeast, suggesting that these genes encode functional IPMDH. RT-PCR analysis revealed different tissue specificity of transcript accumulation for the three genes.