The novel genes, cbbQ and cbbO, located downstream from the RubisCO genes of Pseudomonas hydrogenothermophila, affect the conformational states and activity of RubisCO

The cbbQ and cbbO genes are located downstream from the RubisCO genes (cbbLS) in the thermophilic hydrogen-oxidizing bacterium, Pseudomonas hydrogenothermophila. Recombinant RubisCO enzymes were purified from E. coli cells which were transformed with plasmids expressing cbbLS, cbbLSQ cbbLSO, or cbbLSQO. Go-expression of cbbQ and/or cbbO with cbbLS made the maximal rates of carboxylation (Vmax) of the recombinant RubisCOs about twofold higher than that of the enzyme derived from only cbbLS. The RubisCOs with high Vmax also had a high stability when undergoing ultrasonic treatment. The results of the circular dichroism spectra and the 8-anilino-1-naphthalenesulfonate binding assay indicated that these recombinant RubisCOs were conformationally different to each other. (C) 1997 Academic Press.