Synthetic Biology Pathways to Isoquinoline Alkaloids

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For thousands of years mankind has been using plants and medicinal compounds from plants for treating pain, diseases, infections and also for recreational purposes. Many of these plant derived compounds have also found their way into modern drug use for example morphine and codeine for pain relief, atropine to increase heart rate and for irritable bowel syndrome, vinblastine to treat cancers and quinine for malaria. There are over 14,000 alkaloid chemical structures known and these represent a wealth of potential biological activity. However many of these alkaloids occur in small amounts or in plants that are rare or only grow in parts of the world that are difficult to access. The pathways that plants use to synthesise alkaloids are often long with many biosynthetic steps. There are some key intermediate compounds that are common to many plant alkaloid pathways and the complexity of alkaloid structures comes from the different later steps in the pathways that different plants have. It would be of great benefit to be able to make some of these key intermediate alkaloid compounds in a more controlled way and to be able to modify these alkaloid structures using enzymes or chemistry. In this way novel biologically active drugs could be found. The pathways for the synthesis of several alkaloids have begun to be determined but many of the steps for some of the more complex alkaloids are still unknown. In the last few years researchers have begun to isolate the enzymes (and their genes) for some of the key steps in the synthesis of some alkaloids. Some of these enzymes carry out very important steps such as the joining together of rather simple compounds derived from simple amino acids. We intend to use the techniques of whole gene synthesis, synthetic biology and pathway design to make some of these key alkaloid synthesising enzymes and put them into a laboratory bacterium. In this way we can combine different plant based and bacterial enzymes and build synthetic pathways for the creation of new chemical compounds that could be screened for useful medicinal activities. By having the pathways in bacteria we would be able to generate them in a reproducible way using a renewable resource and not be dependant on the growth of difficult or rare plants. In addition, extensive chemical transformations using methods with high environmental impact would not be required which are currently used to synthesise such isoquinolines.