Ispoentenyl pyrophosphate isomerases from Melaleuca alternifolia (Cheel) and their role in isoprenoid biosynthesis

Two cDNA clones, idi1 and idi2, representing different isoforms of isopentenyl pyrophosphate isomerase (IPP isomerase) were isolated from Melaleuca alternifolia (Cheel) by functional complementation of carotenoid biosynthesis in E. coli.. Excluding the putative transit peptide region, share 89.5% predicted protein sequence identity. The high level of conservation between the isoforms indicates that these genes may share a common ancestral origin and supports the proposition that cytosolic and plastid targeted IPP isomerase may be differentially translated from a single gene. This study supports recent evidence suggesting that isopentenyl pyrophosphate and dimethylallylic pyrophosphate are both immediate products of the deoxyxylulose pathway and that IPP isomerase may have a more central role in the biosynthesis of carotenoids than in the biosynthesis of monoterpenes.