リジンからアルカロイド生産への代謝分岐

抄録

The decarboxylation of a basic aliphatic amino acid, lysine, is the first step of biosynthesis of large family of plant alkaloids, such as quinolizidine and lycopodium alkaloids. Produced cadaverine is incorporated into alkaloid molecules like as building blocks to form diverse molecular structures. In plants, lysine decarboxylation is catalyzed by a bifunctional lysine/ornithine decarboxylase (L/ODC) which had been evolutionally derived from omnipresent ornithine decarboxylase (ODC). An amino-acid substitutions from His residue to Phe or Tyr were found between ODC and L/ODC near the active center. These substitutions to aromatic residues determine the cavity size of L/ODC, which arise the acceptability of both ornithine and lysine as substrates and bifunctionality of enzymes. L/ODC genes were found specifically in the species producing lysine-derived alkaloids and soybean producing cadaverine. From these results, the presence of L/ODC should be the trigger of alkaloid production. Furthermore, metabolic engineering using lupin L/ODC was performed to create new metabolic flow in model plants.