Molecular cloning and functional identification of a cDNA encoding 4-hydroxy-3-methylbut-2-enyl diphosphate reductase from

ABSTRACT

The 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) is the last step key enzyme of the methylerythritol phosphate (MEP) pathway, synthesizing isopentenyl diphosphate and its allyl isomer dimethylallyl diphosphate, which is important for regulation of isoprenoid biosynthesis. Here the full-length cDNA of, designated(GenBank Accession No. KJ933412.1), was isolated fromfor the first time. TwHDR has an open reading frame (ORF) of 1386 bp encoding 461 amino acids. TwHDR exhibits high homology with HDRs of other plants, with an N-terminal conserved domain and three conserved cysteine residues.cDNA was cloned into an expression vector and transformed into anmutant. Since loss-of-functionmutant is lethal, the result showed that transformation ofcDNA rescued themutant. This complementation assay suggests that thecDNA encodes a functional HDR enzyme. The expression ofwas induced by methyl-jasmonate (MJ) insuspension cells. The expression ofreached the highest level after 1 h of MJ treatment. These results indicate that we have identified a functional TwHDR enzyme, which may play a pivotal role in the biosynthesis of diterpenoid triptolide in.