Cutting respiration
Plants spend half their carbon fixed by photosynthesis on respiratory processes. This is energy used for generation of ATP and reducing equivalents, uptake and assimilation of nutrients, maintenance of cell structures, etc. Carbon spent on respiration can never be used for biomass production instead is released back into the atmosphere as carbon dioxide. To increase biomass production in crops, we aim at cutting carbon loss by respiration. Such saved carbon might be rechanneled into the production of harvestable yield.
Maintenance of proteins consumes up to 15% of a plant’s total carbon budget and is therefore a profitable target for crop engineering. Short-lived enzymes are particularly costly to plants. These are proteins which catalyze only a small number of reactions before they must be replaced. Replacing them in plants with engineered versions which can turn over thousands or millions of reactions may free energy for biomass production.
We use continuous directed evolution in yeast to expand the working life of plant enzymes. Native genes in model crops such as tomato will then be replaced by evolved one to examine its functionality in planta.
We use continuous directed evolution in yeast to expand the working life of plant enzymes. Native genes in model crops such as tomato will then be replaced by evolved one to examine its functionality in planta.
Alternative carbon fixation
“Rubisco is stuck in evolution”. This is a common statement about the most abundant protein on earth. It may or may not be possible to engineer it, however, many tried and failed. Still, increasing the carbon fixation rate in crops is crucial to increase biomass production. Using synthetic biology, we are exploring alternative carbon fixation and how it can be manipulated to benefit crop performance.
Enzyme and amino acid damage repair
Enzymes get damaged from the inside and the outside. In aerobic organism, they face reactive oxygen species which oxidize amino acids; methionine and cysteine are particularly susceptible to it. Nature has evolved repair mechanisms to restore enzyme function and to reduce oxidized residues back to their native form. However, these repair mechanisms are often limited in what they can do and how efficient they are. By engineering repair enzymes, we envision to expand and improve they activity aiming at generating crops which are more resilient against stress.
