Improvement of cyanobacterial RuBisCO by introducing the latch structure of red algal RuBisCO with high specificity for CO₂ fixation.

Abstract

Ribulose 1,5-bisphosphate carboxylase oxygenase ( RuBisCO ) catalyzes both carboxylation and oxygenation reactions of RuBP. The specificity for carboxylation relative to oxygenation is represented by S_rel (S_rel = Vmax(CO₂) Km(O₂) / Vmax(O₂) Km(CO₂) ). We expect that the creation of RuBisCO with high S_rel enables plants to acquire high photosynthetic efficiency.
RuBisCO of red alga Galdieria partita shows the highest S_rel of 238 among RuBisCOs examined so far. Galdieria RuBisCO has a unique structure involved in high S_rel. This structure is a hydrogen bond called the latch structure between the main chain oxygen of Val332 and the amino group of Gln386. No latch structure can be seen in plant and cyanobacterial RuBisCOs.
To clarify the relationship between S_rel and the latch structure, we introduced the latch structure into cyanobacterial RuBisCO known to show low S_rel . Mutant RuBisCO was likely to show higher S_rel than that of wild type.