Heterologous assembly of red-type Rubisco and functional identification of chaperonin in Porphyridium purpureum

Abstract

In the natural growth process of organisms, Ribulose 1,5-diphosphate carboxylase/oxygenase (Rubisco) is the rate-limiting enzyme for carbon fixation in photosynthesis. However, its carboxylation is low and the reaction can be competitively inhibited by O2. Red-type Rubiscos are known with higher catalytic rates and CO2/O2 specificity, but their incompatibility with chaperonins in the green lineage pose challenges for them to be assembled and accumulated in C3 plants. In this study, we systematically explored the factors and conditions required for heterologous accumulation Rubisco from Porphyridium purpureum and that from Phaeodactylum tricornutum. We found that P. purpureum Rubisco required less co-factors to be produced in Escherichia coli than the P. tricornutum needed. In addition, the amino acid sequences of the co-chaperonin Cpn10 and Cpn20 in P. purpureum were retrieved, and they can assist in GroEL to fold the red-type Rubisco large subunits in vitro and in E. coli. Heterogeneous system research on Rubisco assembly conditions are of great significance for humans to understand CO2 fixation mechanism, improve crop yield and mitigate global climate change.