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 Srel (Srel = Vmax(CO2) Km(O2) / Vmax(O2) Km(CO2) ). We expect that the creation of RuBisCO with high Srel enables plants to acquire high photosynthetic efficiency.
RuBisCO of red alga Galdieria partita shows the highest Srel of 238 among RuBisCOs examined so far. Galdieria RuBisCO has a unique structure involved in high Srel. 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 Srel and the latch structure, we introduced the latch structure into cyanobacterial RuBisCO known to show low Srel . Mutant RuBisCO was likely to show higher Srel than that of wild type.