Can efficient algal variants of the photosynthetic CO2-fixing enzyme, Rubisco, be folded and assembled in functional forms in higher-plant plastids? We have shown that it is possible to alter the photosynthetic phenotype of a plant predictably and profoundly by engineering the plastid genome to replace the plant's CO2-fixing enzyme, Rubisco, with a bacterial homolog. Thus it may be possible to replace the plant enzyme with more efficient algal Rubiscos that would allow plants to grow with less l ....Can efficient algal variants of the photosynthetic CO2-fixing enzyme, Rubisco, be folded and assembled in functional forms in higher-plant plastids? We have shown that it is possible to alter the photosynthetic phenotype of a plant predictably and profoundly by engineering the plastid genome to replace the plant's CO2-fixing enzyme, Rubisco, with a bacterial homolog. Thus it may be possible to replace the plant enzyme with more efficient algal Rubiscos that would allow plants to grow with less light, less water or less fertiliser. Before such desirable changes to the plant phenotype can be realised, some complex issues of modification, folding and assembly of Rubisco subunits need to be resolved. This proposal addresses them.Read moreRead less
Role of alanine aminotransferase in improved nitrogen use efficiency (NUE) in cereals. The use of nitrogen-based fertilisers by crop plants is poor where efficiencies (nitrogen taken up to that applied) is often less than 40%. Nitrogen not used is often lost to the environment through leaching and or volatilisation. Improving nitrogen use efficiency (NUE) in agriculture will decrease overall nitrogen fertiliser use and minimise its environmental footprint. This project will characterise a nov ....Role of alanine aminotransferase in improved nitrogen use efficiency (NUE) in cereals. The use of nitrogen-based fertilisers by crop plants is poor where efficiencies (nitrogen taken up to that applied) is often less than 40%. Nitrogen not used is often lost to the environment through leaching and or volatilisation. Improving nitrogen use efficiency (NUE) in agriculture will decrease overall nitrogen fertiliser use and minimise its environmental footprint. This project will characterise a novel NUE technology that when transferred to plants significantly improves NUE. We will define the phenotype at the molecular, biochemical and physiological levels to maximise its adoption to other agricultural crops such as wheat, barley and maize.Read moreRead less
Enhancing plant photosynthesis by engineering the carbon dioxide (CO2)-fixing enzyme Rubisco. Improving the ability of crops to use water, sunlight and fertiliser more efficiently would have economic benefits for Australia and ease the environmental impacts associated with agricultural practices. Photosynthesis research has confirmed that such improvements are theoretically possible by enhancing the efficiency of the protein, Rubisco, which initiates the conversion of carbon dioxide into carbon ....Enhancing plant photosynthesis by engineering the carbon dioxide (CO2)-fixing enzyme Rubisco. Improving the ability of crops to use water, sunlight and fertiliser more efficiently would have economic benefits for Australia and ease the environmental impacts associated with agricultural practices. Photosynthesis research has confirmed that such improvements are theoretically possible by enhancing the efficiency of the protein, Rubisco, which initiates the conversion of carbon dioxide into carbon compounds required for growth. The biotechnological research proposed here uses unique capabilities to improve our understanding of structural features in Rubisco that influence its assembly and functional efficiency in plants. This knowledge will pave the way for transplanting more efficient Rubisco into crops to improve their growth.Read moreRead less
Practical strategies for engineering the CO2-fixing enzyme, Rubisco, whose subunits are encoded in different subcellular compartments. My recent replacement of the plant CO2-fixing enzyme, Rubisco, with a less efficient bacterial version, with a single type of subunit encoded by a single gene, demonstrated the feasibility of replacing Rubisco. This encourages ongoing attempts to replace plant Rubisco with more efficient versions that would allow the plants to grow with less water, fertiliser or ....Practical strategies for engineering the CO2-fixing enzyme, Rubisco, whose subunits are encoded in different subcellular compartments. My recent replacement of the plant CO2-fixing enzyme, Rubisco, with a less efficient bacterial version, with a single type of subunit encoded by a single gene, demonstrated the feasibility of replacing Rubisco. This encourages ongoing attempts to replace plant Rubisco with more efficient versions that would allow the plants to grow with less water, fertiliser or light. The most efficient Rubiscos are more complex, with two different types of subunits which, in plants, are encoded in different subcellular compartments (nucleus and plastid). This proposal addresses the challenges associated with complementary engineering both genomes to substitute foreign Rubiscos into higher-plant chloroplasts.Read moreRead less
Controlling the rate of transcription and translation of Rubisco transgenes effectively in higher-plant plastids. Genetic transformation of the circular genome of the plastids provides a containable means for modifying plant growth by manipulating photosynthesis. Although the transformation mechanism is precise, predicting the level of foreign gene expression is difficult because the amounts of messenger RNA and protein produced by foreign genes in plastids varies widely, even when the protein a ....Controlling the rate of transcription and translation of Rubisco transgenes effectively in higher-plant plastids. Genetic transformation of the circular genome of the plastids provides a containable means for modifying plant growth by manipulating photosynthesis. Although the transformation mechanism is precise, predicting the level of foreign gene expression is difficult because the amounts of messenger RNA and protein produced by foreign genes in plastids varies widely, even when the protein assembles without difficulty. This project will devise strategies for controlling this variability that will facilitate attempts to exploit plastid transformation for transplanting better versions of the photosynthetic CO2-fixing enzyme, Rubisco, into plants to improve their growth efficiency in terms of water, fertiliser and light use.Read moreRead less
Identifying potential barriers to transplanting modified forms of the CO2-fixing enzyme, Rubisco, into plants. Improving the ability of crops to use water, light and fertiliser more efficiently would have economic benefits and ease the environmental impacts associated with agricultural practices. It is thought that such improvements can be made by enhancing the efficiency of the photosynthetic protein, Rubisco, which fixes most of the CO2 in the biosphere. The research proposed here uses unique ....Identifying potential barriers to transplanting modified forms of the CO2-fixing enzyme, Rubisco, into plants. Improving the ability of crops to use water, light and fertiliser more efficiently would have economic benefits and ease the environmental impacts associated with agricultural practices. It is thought that such improvements can be made by enhancing the efficiency of the photosynthetic protein, Rubisco, which fixes most of the CO2 in the biosphere. The research proposed here uses unique Rubisco transplantation capabilities that I have developed to improve our fundamental understanding of how Rubisco is processed and its activity regulated in plants. This will pave the way for our ongoing efforts to engineer and transplant more efficient Rubisco into crops.Read moreRead less
The structure and function of cyanobacterial carboxysome multi-protein complexes and their role in carbon sequestration in cyanobacteria. Cyanobacteria are important contributors to global photosynthesis and have evolved unique mechanisms for capturing CO2 from their aquatic environments. Understanding these molecular mechanisms is important for both predicting how cyanobacteria affect carbon fixation at the global scale, and how their genetic specialisation may be used for improving photosynthe ....The structure and function of cyanobacterial carboxysome multi-protein complexes and their role in carbon sequestration in cyanobacteria. Cyanobacteria are important contributors to global photosynthesis and have evolved unique mechanisms for capturing CO2 from their aquatic environments. Understanding these molecular mechanisms is important for both predicting how cyanobacteria affect carbon fixation at the global scale, and how their genetic specialisation may be used for improving photosynthesis in agricultural plants. This project aims to examine one particular aspect of this specialisation, the multi-protein carboxysome complex, where CO2 fixation occurs. Using recent whole-genome information we will take a proteogenomic approach to understanding the structure and function of the carboxysome and how it contributes to the photosynthesis of the cell.Read moreRead less
Active bicarbonate transporters from cyanobacteria: physiological properties, genetic regulation, and introduction into plants for crop improvement. An intriguing set of membrane transport proteins that accumulate bicarbonate into marine cyanobacterial cells will be investigated. These proteins support the crucial process of photosynthetic carbon dioxide fixation in marine cyanobacteria (blue-green algae), which are major contributors to global carbon dioxide sequestration and form one of the f ....Active bicarbonate transporters from cyanobacteria: physiological properties, genetic regulation, and introduction into plants for crop improvement. An intriguing set of membrane transport proteins that accumulate bicarbonate into marine cyanobacterial cells will be investigated. These proteins support the crucial process of photosynthetic carbon dioxide fixation in marine cyanobacteria (blue-green algae), which are major contributors to global carbon dioxide sequestration and form one of the foundations of the marine food web. These bicarbonate "transporters" will also be transferred into a model plant system to test whether the efficiency of photosynthesis can be improved, with corresponding gains in the water-use efficiency of these plants. If successful this technology will have profound global implications for improving crop production in semi-arid areas.Read moreRead less
Organophosphate pesticide degradation: evolved enzymes and biomimetics for bioremediation and medicine. Organophosphate (OP) pesticides are an indispensable part of modern agriculture - their use results in dramatically increased crop yields. However, they are toxic and can damage the environment and cause significant health problems. Enzymes are currently being used to treat runoff water that is contaminated with OPs. The same enzymes also have the potential to aid in the treatment of OP poison ....Organophosphate pesticide degradation: evolved enzymes and biomimetics for bioremediation and medicine. Organophosphate (OP) pesticides are an indispensable part of modern agriculture - their use results in dramatically increased crop yields. However, they are toxic and can damage the environment and cause significant health problems. Enzymes are currently being used to treat runoff water that is contaminated with OPs. The same enzymes also have the potential to aid in the treatment of OP poisoning. However, OP degrading enzymes could be improved in many ways - we will evolve these enzymes to enhance their catalytic properties - to enable them to act more efficiently on an increased number of OPs. Read moreRead less
Role of a novel zinc-binding motif in the structure-function of deubiquitinating enzymes. The ubiquitin pathway destroys many proteins that control cell function and growth, by attaching ubiquitin to them and marking them for degradation. Deubiquitinating enzymes (DUBs) regulate protein destruction by controlling the amount of ubiquitin attached. DUBs and the ubiquitin pathway can also be manipulated in biotechnology applications. However, very little is known about the structure/function of DUB ....Role of a novel zinc-binding motif in the structure-function of deubiquitinating enzymes. The ubiquitin pathway destroys many proteins that control cell function and growth, by attaching ubiquitin to them and marking them for degradation. Deubiquitinating enzymes (DUBs) regulate protein destruction by controlling the amount of ubiquitin attached. DUBs and the ubiquitin pathway can also be manipulated in biotechnology applications. However, very little is known about the structure/function of DUBs. We have identified a new zinc-binding motif in DUBs, and we will explore how this contributes to their structure, and interactions with other proteins. This will significantly enhance our knowledge of how DUBs function in both biotechnology and in controlling cell function.Read moreRead less