Small subunits can determine enzyme kinetics of tobacco Rubisco expressed inEscherichia coli

Ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) catalyses the first step in carbon fixation and is a strategic target for improving photosynthetic efficiency. In plants, Rubisco is composed of eight large and eight small subunits, and its biogenesis requires multiple chaperones. Here, we optimized a system to produce tobacco Rubisco inEscherichia coliby coexpressing chaperones in autoinduction medium. We successfully assembled tobacco Rubisco inE. coliwith each small subunit that is normally encoded by the nuclear genome. Even though each enzyme carries only a single type of small subunit inE. coli, the enzymes exhibit carboxylation kinetics that are very similar to the carboxylation kinetics of the native Rubisco. Tobacco Rubisco assembled with a recently discovered trichome small subunit has a higher catalytic rate and a lower CO(2)affinity compared with Rubisco complexes that are assembled with other small subunits. OurE. coliexpression system will enable the analysis of features of both subunits of Rubisco that affect its kinetic properties. In plants, Rubisco is composed of 16 subunits and requires multiple chaperones to assemble. Features of individual tobacco Rubisco subunits that affect kinetic properties are investigated by coexpression with chaperones inEscherichia coli.