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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Evolving novel carbon dioxide reducing enzymes

Alternative title: Utvikling av nye enzymer som reduserer og fikserer karbondioksid

Awarded: NOK 12.0 mill.

Each year, more than 350 gigatons of carbon dioxide are converted to biomass by plants and microorganisms. This process is part of the carbon cycle that describe the overall distribution of carbon on planet Earth. Plant and microorganisms use enzymes to convert carbon dioxide to biomass. The bottleneck in this process is an enzyme called rubisco which is quite slow. The project COOFIX aims to develop novel enzymes that can function as a supplement for rubisco in photosynthetic organisms and standalone catalysts for carbon dioxide capture in industrial settings. To achieve our goals, we will take advantage of knowledge already generated in the laboratories of chemists and modify enzymes that contain metal ions like copper to mimic carbon dioxide reactions observed in their experiments. Our strategy is to combine rational design and directed evolution methodologies. The rational design approach requires application of state-of-the art methods in molecular modeling and computational chemistry, and we will take advantage of available national supercomputer facilities to aid our experiments. Discoveries made using computational chemistry must be expanded on in the laboratory. The most effective approach to optimize enzyme functionality in the laboratory is called directed evolution. Here, we take advantage of modern DNA technology to identify enzyme candidates that can convert carbon dioxide to none-gaseous molecules that are highly soluble in water. In the first year of the project, we have started the characterization of several enzyme candidates. Pipelines have been established for efficient production of enzymes, these are now characterized by biochemical methods, structural biology and computational chemistry. At the same time, we are working on developing software that enables us to capture the diversity of the amino acid side chains that bind metal ions in the active sites of these enzymes. This is important in order to explore the catalytic properties of the enzyme candidates. In the last part of the project we will apply methodology called metabolic engineering. Here we will alter the metabolic pathways in selected organisms so that the molecules generated from carbon dioxide by our novel enzymes can efficiently be converted to biomass. Our ultimate goal is to contribute a sustainable and novel method of carbon dioxide utilization/capture to the society.

Each year, more than 350 gigatons of carbon dioxide are converted to biomass by autotrophs, sustaining life on Earth with reduced carbon compounds. The rate limiting enzyme of carbon dioxide assimilation is called RubisCO, which is remarkably slow and inefficient, wasting huge amounts of the energy harvested from the sun. COOFIX aims to design a novel enzyme that can fix carbon dioxide into the metabolic intermediate oxalate in a single step. COOFIX employ a highly interdisciplinary approach, combining biochemistry, spectroscopy, structural biology and computational chemistry in an innovative manner to accomplish the project objectives. Binuclear organometallic copper complexes are capable of reducing carbon dioxide to oxalate with high selectivity, and this functionality will be engineered in type-3 copper protein active sites. An autotrophic model organism will be engineered to accommodate our novel carbon dioxide reductase and to convert the enzyme product oxalate to biomass. A novel method of computer assisted enzyme engineering is proposed to efficiently improve our carbon dioxide reducing enzyme. Current computational engineering methods are limited by inefficient sampling of fluctuating protein structures along the evolutionary path. COOFIX combine hardware and software accelerated molecular dynamics simulations with machine learning to address this challenge. COOFIX will contribute to groundbreaking discoveries in the fields of synthetic biology and enzyme engineering. It will also impact carbon dioxide feedstock utilization, providing novel opportunities to accumulate valuable organic molecules from this surplus and underexploited resource.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek