ANALYSIS OF THE DNA DAMAGE-MEDIATED INDUCTION OF PSEUDOMONAS-PUTIDA AND PSEUDOMONAS-AERUGINOSA LEXA GENES

A fusion between the lexA gene of Pseudomonas aeruginosa and Pseudomonas putida and the lacZ gene was constructed in vitro and cloned in a mini-Tn5 transposon derivative to obtain chromosomal insertions which enable to quantitatively examine their transcriptional regulation in both Pseudomonas and E. coli. Analysis of DNA damage-mediated induction of these lexA-lacZ fusions showed that expression of P. putida and P. aeruginosa lexA genes was always higher and earlier than the expression of the lexA gene of E. coli. Furthermore, and in contrast to the letA gene fusion of E. coli, the rates and extent of the induction of lexA gene fusion of P. putida and P. aeruginosa were largely independent of the UV doses applied. The behaviour of the lexA-lacZ fusions of two Pseudomonas species was the same regardless of whether they were inserted into their own chromosome or into E. coli.