The final puzzle piece in the chemical pathway that makes morphine has been identified, scientists report June 25 in Science. The work fills in the center piece in the path — the protein converting the compound (S)-reticuline to (R)-reticuline.
By analyzing poppy DNA and confirming its function in yeast, the researchers showed that a single gene produces an enzyme made of two parts, each of which controls a step of the conversion of reticuline.
This protein links the previously known beginning and end steps in the morphine-making pathway. Both the beginning and end steps have already been engineered in separate yeast strains. Putting the three parts of the pathway together will eventually result in yeast that produce morphine.