22BBSRC-NSF/BIO: A synthetic pyrenoid to guide the engineering of enhanced crops
Lead Research Organisation:
University of York
Department Name: Biology
Abstract
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Technical Summary
In this project we will use in vitro reconstitution and modelling to guide and rapidly accelerate the engineering of a functional pyrenoid-based CO2-concentrating mechanism (CCM) into the model C3 plant Arabidopsis. One of the key growth bottlenecks in C3 crop plants is the slow rate of photosynthetic CO2 capture by the CO2-fixing enzyme Rubisco. Pyrenoid-based CCMs overcome this shortcoming by condensing Rubisco into a spherical compartment called the pyrenoid, wherein Rubisco is fed with a high concentration of CO2 to maximise carboxylation rates and minimise the competing oxygenase activity of Rubisco. Pyrenoids in the green alga Chlamydomonas reinhardtii are traversed by modified photosynthetic thylakoid membranes known as pyrenoid tubules, which are understood to deliver concentrated CO2 to Rubisco through the activity of a specialised carbonic anhydrase that leverages the low pH inside the thylakoid lumen to convert bicarbonate into CO2. The bicarbonate enters the tubules from the surrounding stroma via bicarbonate channels in the thylakoid membranes bordering the pyrenoid.
Our labs have recently discovered the identities of the key components required for Rubisco matrix assembly, tubule biogenesis, and the supply of CO2 to Rubisco. Together, these findings will allow us to advance our basic understanding of the principles that underlie the pyrenoid-based CCM, build a cell-free minimal pyrenoid-based CCM, test a functional pyrenoid-based CCM in Arabidopsis, and lay the groundwork for a high-efficiency pyrenoid supported by a CO2 diffusion barrier. The project has three experimental aims each supported by computational modelling (see Objectives). Our efforts to reconstitute a pyrenoid assembly in vitro and to engineer a plant-based pyrenoid will push the boundaries of plant engineering biology and will advance our fundamental understanding of the principles that underpin the functioning of pyrenoid-based CCMs.
Our labs have recently discovered the identities of the key components required for Rubisco matrix assembly, tubule biogenesis, and the supply of CO2 to Rubisco. Together, these findings will allow us to advance our basic understanding of the principles that underlie the pyrenoid-based CCM, build a cell-free minimal pyrenoid-based CCM, test a functional pyrenoid-based CCM in Arabidopsis, and lay the groundwork for a high-efficiency pyrenoid supported by a CO2 diffusion barrier. The project has three experimental aims each supported by computational modelling (see Objectives). Our efforts to reconstitute a pyrenoid assembly in vitro and to engineer a plant-based pyrenoid will push the boundaries of plant engineering biology and will advance our fundamental understanding of the principles that underpin the functioning of pyrenoid-based CCMs.
