Phycocyanin promoter of Spirulina platensis controlling heterologous expression in cyanobacteria

An efficient expression vector for transferring exogenous deoxyribonucleic acid (DNA) into cell is important for biological study and recombinant protein production in cyanobacteria. The promoter, which can mediate gene expression and function in both Escherichia coli and cyanobacteria, could facilitate development of an expression vector for a DNA transfer system in cyanobacteria. Computational analysis of the phycocyanin (PC) promoter of Spirulina platensis strain C1 showed a high degree of conservation with the PC promoter of other cyanobacteria. In addition, the S. platensis PC promoter matched well with the consensus sequences of the E. coli promoter. Using green fluorescent protein (GFP) as a reporter, activity of the PC promoter of S. platensis C1 was functionally analyzed in Synechococcus elongatus and E. coli. The result revealed that the PC promoter could efficiently drive gfp expression in heterologous hosts, indicating the existence of common transcription machinery in these microbes. This promoter may be applicable not only for fundamental research but also for biotechnological purposes.