Basic analysis of rpoS mutation on two gene clusters of phenazine in Psedomonas aeruginosa PAO

Abstract:

Abstract：As an opportunistic pathogen, Pseudomonas aeruginosa PAO1 can produce phenazine and its derivatives, which play a critical role in their pathogenesis. In many bacteria, RpoS, the product of rpoS gene, mediates biosynthesis of a set of secondary metabolites. [Objective] This study aims to elucidate rpoS gene’s function and regulation on two phenazine gene clusters in Pseudomonas aeruginosa PAO1. [Methods] The rpoS gene and its upstream and downstream fragments were cloned from the chromosome of Pseudomonas aeruginosa. With the insertion of gentamycin resistance cassette (aacC1), the mutant PA-SG has been created by homologous recombination. Translational fusion plasmids phz1′-′lacZ(pMEZ1) and phz2′-′lacZ(pMEZ2) were constructed, and then were introduced into the wild type strain PAO1 and the mutant PA-SG, respectively. Activities of beta-galactosidase in them were determined with Miller method. [Results] In KMB or PPM medium, beta-galactosidase activity of phz1′-′lacZ in the mutant PA-SG is much more than that in the wild type strain. However, beta-galactosidase activity of phz2′-′lacZ in the wild type strain is 2-3 folds more than that in the mutant PA-SG. [Conclusion] With these results, it is suggested that regulation mediated by rpoS gene on two phenazine loci is specific and different.