CONSTRUCTION OF LACZ PROMOTER PROBE VECTORS FOR USE IN SYNECHOCOCCUS - APPLICATION TO THE IDENTIFICATION OF CO2-REGULATED PROMOTERS

It was shown that the Escherichia coli lacZ gene could be expressed in the cyanobacterium Synechococcus R2 PCC7942 both as a plasmid-borne form and also integrated into the chromosome. A promoterless form of the lacZ gene was constructed and used as a reporter gene to make transcriptional fusions with cyanobacterial promoters using a shuttle vector system and also via a process of integration by homologous recombination. Synechococcus R2 promoter-lacZ gene fusions were then used to identify CO2-regulated promoters, by quantitatively assessing β-galactosidase activity under high and low CO2 conditions using a fluorescence assay. Several promoters induced under low CO2 conditions were detected. © 1990.