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 Pseudomon as putida and the lacZ gene was constructed in vitro and cloned in a m ini-Tn5 transposon derivative to obtain chromosomal insertions which e nable to quantitatively examine their transcriptional regulation in bo th 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 expressio n of the lexA gene of E. coli. Furthermore, and in contrast to the let A gene fusion of E. coli, the rates and extent of the induction of lex A 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 inse rted into their own chromosome or into E. coli.