Identification, characterization and sequence analysis of the gene encoding phosphoenolpyruvate carboxylase in Anabaena sp. PCC 7120.

The gene (ppc) encoding phosphoenolpyruvate carboxylase (PEPCase) in the cyanobacterium Anabaena sp. PCC 7120 has been isolated, characterized and its nucleotide sequence determined. Heterologous hybridization using the Synechococcus sp. PCC 7942 ppc gene as a probe of an Anabaena genomic DNA library identified an 8.2 kb HindIII DNA fragment that contained a 3.08 kb open reading frame encoding the cyanobacterial PEPCase. Deletion analysis of the 8.2 kb DNA fragment was used to determine sequences required for expression of enzyme activity in Escherichia coli cells. Primer extension data have been used to identify the cyanobacterial transcription initiation site and the position of the ppc start codon. Comparisons of the Anabaena deduced amino acid sequence with the Synechococcus sp. PCC 6301, E. coli and higher-plant ppc sequences have also been performed and the data are discussed with respect to conservation of specific regions of the protein.