Unknown,Transcriptomics,Genomics,Proteomics

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Regulon of transcriptional regulator PA2449 in Pseduomonas aeruginosa PAO1

ABSTRACT: The putative trancriptional regulator PA2449 was found to be essential for both glycine/serine metabolism and the production of phenazines in P. aeruignosa PAO1. We examined the regulon controlled by PA2449 via microarray analysis between wild-type P. aeruignosa PAO1 and the PA2449-null mutant P. aeruginosa PW5126. Both strains were obtained from the PA-two allele library (Univ. of Washington, Ref. Jacobs et al. 2003. PNAS 100, 14339). Strains were grown under conditions known to induce phenazine biosynthesis (peptone broth), and their resulting transcriptomes were compared. Total RNA was isolated and prepped for Affymetrix GeneChips.

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Christopher Nomura

PROVIDER: E-GEOD-39044 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The GacS/GacA two component regulatory system globally activates the production of secondary metabolites including phenazines in Pseudomonas chlororaphis 30-84. To better understand the regulatory role of the Gac system, we conducted RNA-seq analyses to determine the regulon of the response regulator GacA. Transcriptome analyses identified over 700 genes differentially regulated by GacA. Consistent with our previous findings, phenazine biosynthetic genes were significantly down-regulated in a gacA mutant. The expression levels of phenazine regulatory genes such as phzI, phzR, iopA, iopB, rpoS and pip were also decreased. Moreover, the expression of three none-coding RNAs (ncRNAs) including rsmX, rsmY and rsmZ was significantly decreased by gacA mutation consistent with the presence of GacA binding sites in their promoters. Our results also demonstrated that over-expression of rsmZ from a non-gac regulated promoter resulted in the restoration of AHL and phenazine production as well as the expression of other secondary metabolites in gac mutants. The role of RsmA and RsmE in phenazine production was also investigated. Over-expression of rsmE, but not rsmA, resulted in decreased AHL production and phenazine gene expression in P. chlororaphis. Consistently, a mutation in rsmE bypassed the requirement of GacA in phenazine gene expression. On the contrary, constitutive expression of the phzI/phzR quorum sensing system was not able to rescue phenazine production in the gacA mutant indicating the direct impact of Gac system on the transcript stability of phenazine biosynthetic genes. Together, these results indicate that the Gac system regulates phenazine production at multiple levels and exerts its positive effect on AHL and phenazine biosynthesis via RsmZ and RsmE. A model is proposed to illustrate the GacA regulon in P. chlororaphis 30-84. A total of 6 samples were analyzed in AB medium + 2% casamino acids, Pseudomonas chlororaphis wild type strain (3 replicates); Pseudomonas chlororaphis gacA mutant (3 replicates).