title: Assembly of cyanobacterial and higher plant ribulose bisphosphate carboxylase subunits into functional homologous and heterologous enzyme molecules in Escherichia coli.
abstract: The genes for the large (rbcL) and small (rbcS) subunits of ribulose-1,5 bisphosphate carboxylase-oxygenase (RuBPCase) from the cyanobacterium Synechococcus PCC 6301, and the rbcS gene of wheat, have been expressed in Escherichia coli in order to study homologous and heterologous enzyme assembly. Synechococcus L subunits expressed in E. coli in the absence of S subunits assemble into oligomeric structures without detectable enzyme activity. Co-expression of L and S subunits, achieved after infection with an M13 recombinant phage containing the rbcS gene, restores enzyme activity, thus demonstrating the essential role of S in the formation of an active RuBPCase. The S subunit, however, is neither required for the solubility nor for the assembly of the L subunits into oligomeric forms. The specific activity of the homologous Synechococcus RuBPCase can be modulated by changing the intracellular pool size of S by phage infection. Heterologous assembly between L subunits of Synechococcus and S subunits of wheat can be demonstrated and results in a functional enzyme. The hybrid RuBPCase has approximately 10% of the activity of the homologous Synechococcus enzyme.
authors.affiliation: Department of Biochemistry, Agricultural University, Wageningen, The Netherlands.
authors.forename: S M
authors.initials: SM
authors.lastname: van der Vies
authors.forename: D
authors.initials: D
authors.lastname: Bradley
authors.forename: A A
authors.initials: AA
authors.lastname: Gatenby