The Nucleotide Sequence for the Large Subunit of Ribulose 1,5-Bisphosphate Carboxylase from a Unicellular Cyanobacterium,SynechococcusPCC6301

Abstract

The gene for the large subunit (LSU) of ribulose 1,5-bisphosphate carboxylase from a unicellular cyanobacterium, Synechococcus PCC6301, was cloned using the spinach LSU gene as a hybridization probe. The coding region of the Synechococcus LSU gene consists of 1419 nucleotides and shows 70% homology to the spinach nucleotide sequence. The derived amino acid sequence (472 amino acids) shows 81% homology to the spinach LSU and 78% to the maize LSU. Regions containing active-site residues are highly conserved among spinach, maize, and Synechococcus. In contrast, the first 13 amino acids are poorly conserved (30% homology), supporting the hypothesis that this region is proteolytically removed. The 5′-flanking region of the Synechococcus LSU gene contains sequences which correspond to bacterial consensus sequences for the —35 region and Pribnow box. Two 11-bp sequences in the 5′ region show high homology to sequences in spinach and maize. One of these encompasses a possible ribosome-binding site. The 3′-flanking region contains a 35-bp sequence capable of giving rise to a terminator structure.