Plants, ranging from the maple or the yew tree to the corn in roadside fields, produce countless kinds of compounds. These are very useful as antibiotics, anti-cancer drugs or vitamins and are often far too complex to be synthesised successfully in a laboratory, but they can be purified from the plants in which they are found.
This new study, published in the journal ‘Proceedings of the National Academy of Sciences’focused on triterpenes, a large group of plant natural products with a range of biological functions and potential uses in medicine (for example as antimicrobials), industry (for example anti-foaming agents) and also a promising use as a natural sweetener significantly sweeter than sugar.
In particular, the researchers highlight how changing the genetic code for one amino acid in a plant begins a process that alters the shape and function of an enzyme changing the folding of the chemical precursor, a technique that can be considered chemical origami, thus producing a new product with a variety of potential uses. For this study, they changed an amino acid in the first enzyme in a pathway that produces a natural product that protects an oat plant from fungal soil-borne pathogens, thus allowing for disease resistance. This knowledge it is hoped will also be applicable to other crops that will help to protect and potentially increase crop yields.
Plants essentially function as chemical manufacturing factories, and they can be altered to make specific chemical compounds, many of which can be useful in ways we do not yet understand. Altering how an enzyme folds the chemical precursor, resulting in a new compound, is analogous to changing the design or blueprint of a machine tool used in an automotive or refrigerator factory.
‘Changing or modifying plants is not a new concept. Humans have been doing it for thousands of years,’ commented study co-author Robert Minto, associate professor of chemistry and chemical biology from Indiana University–Purdue University Indianapolis. ‘In the PNAS study, we changed a single amino acid in (an enzyme from) the root tip of the oat plant to alter the function of a single enzyme. Being able to go in and do that directly is much more efficient than cross-breeding plants until you finally get the right version of the gene to produce the natural product you desire.’ Minto helped complete the research whilst on a 5-month sabbatical at the UK’s John Innes Centre, a TRIFORC project consortium member.
This study contributes to the overarching ambition of the 4-year TRIFORC project to develop an innovative pipeline for the discovery, sustainable production, and commercial utilisation of known and novel high-value triterpenes with new or superior biological activities. The project is due to complete in September 2017 and has received just under EUR 7 million of EU funding.