Substitution of foreign Rubiscos in the cyanobacterium, Synechococcus PCC7942

Abstract

In cyanobacteria, Rubisco has evolved to be part of a carbon uptake system based on carboxysomes. To study the plasticity of this system and the feasibility of assembling foreign Rubiscos in cyanobacteria, we are supplementing and replacing the cyanobacterial Rubisco with foreign forms of the enzyme that do not assemble into carboxysomes. As a first step, we are deleting the chromosomal rbcLS operon of Synechococcus PCC7942 and complementing the deletion by expression of the Rhodospirillum rubrum rbcL from a shuttle vector. This version of "cyanorubrum " differs from that previously constructed by Pierce et al. (Proc. Natl. Acad. Sci. USA 86: 5753-5757 (1989)) in Synechocystis PCC6803 in that the foreign Rubisco gene is plasmid encoded. This will facilitate substitution and testing of different Rubisco genes and different promoter elements. Results of such substitutions obtained with both the deletion strain and the wild type will be reported.