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Regulation of pyocin genes in Pseudomonas aeruginosa by positive (prtN) and negative (prtR) regulatory genes.

ABSTRACT: Most strains of Pseudomonas aeruginosa produce various types of bacteriocins (pyocins), namely, R-, F-, and S-type pyocins. The production of all types of pyocins was shown to be regulated by positive (prtN) and negative (prtR) regulatory genes. The prtN gene activates the expression of various pyocin genes, probably by the interaction of its product with the DNA sequences conserved in the 5' noncoding regions of the pyocin genes. The prtR gene represses the expression of the prtN gene, and its product, predicted from the nucleotide sequence, has a structure characteristic of phage repressors and seems to be inactivated by the RecA protein activated by DNA damage. A model for the regulation of the pyocin genes is proposed.

SUBMITTER: Matsui H

PROVIDER: S-EPMC193209 | biostudies-other | 1993 Mar

REPOSITORIES: biostudies-other

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Regulation of pyocin genes in Pseudomonas aeruginosa by positive (prtN) and negative (prtR) regulatory genes.

Matsui H H Sano Y Y Ishihara H H Shinomiya T T

Journal of bacteriology 19930301 5

Most strains of Pseudomonas aeruginosa produce various types of bacteriocins (pyocins), namely, R-, F-, and S-type pyocins. The production of all types of pyocins was shown to be regulated by positive (prtN) and negative (prtR) regulatory genes. The prtN gene activates the expression of various pyocin genes, probably by the interaction of its product with the DNA sequences conserved in the 5' noncoding regions of the pyocin genes. The prtR gene represses the expression of the prtN gene, and its ...[more]

PMID: 8444788

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Project description:In Enterobacteriaceae, the transcriptional regulator AmpR, a member of the LysR family, regulates the expression of a chromosomal β-lactamase AmpC. The regulatory repertoire of AmpR is broader in Pseudomonas aeruginosa, an opportunistic pathogen responsible for numerous acute and chronic infections including cystic fibrosis. In addition to regulating ampC, P. aeruginosa AmpR regulates the sigma factor AlgT/U and production of some quorum sensing (QS)-regulated virulence factors. In order to better understand the ampR regulon, we compared the transcriptional profile generated using DNA microarrays of the prototypic P. aeruginosa PAO1 strain with its isogenic ampR deletion mutant, PAOΔampR. Transcriptome analysis demonstrates that the AmpR regulon is much more extensive than previously thought, with the deletion of ampR influencing the differential expression of over 500 genes. In addition to regulating resistance to β-lactam antibiotics via AmpC, AmpR also regulates non-β-lactam antibiotic resistance by modulating the MexEF-OprN efflux pump. Other virulence mechanisms including biofilm formation and QS-regulated acute virulence factors are AmpR-regulated. Real-time PCR and phenotypic assays confirmed the microarray data. Further, using a Caenorhabditis elegans model, we demonstrate that a functional AmpR is required for P. aeruginosa pathogenicity. AmpR, a member of the core genome, also regulates genes in the regions of genome plasticity that are acquired by horizontal gene transfer. Further, we show differential regulation of other transcriptional regulators and sigma factors by AmpR, accounting for the extensive AmpR regulon. The data demonstrates that AmpR functions as a global regulator in P. aeruginosa and is a positive regulator of acute virulence while negatively regulating biofilm formation, a chronic infection phenotype. Unraveling this complex regulatory circuit will provide a better understanding of the bacterial response to antibiotics and how the organism coordinately regulates a myriad of virulence factors in response to antibiotic exposure.

Project description:Ammonia is a major signal that regulates nitrogen fixation in most diazotrophs. Regulation of nitrogen fixation by ammonia in the Gram-negative diazotrophs is well-characterized. In these bacteria, this regulation occurs mainly at the level of nif (nitrogen fixation) gene transcription, which requires a nif-specific activator, NifA. Although Gram-positive and diazotrophic Paenibacilli have been extensively used as a bacterial fertilizer in agriculture, how nitrogen fixation is regulated in response to nitrogen availability in these bacteria remains unclear. An indigenous GlnR and GlnR/TnrA-binding sites in the promoter region of the nif cluster are conserved in these strains, indicating the role of GlnR as a regulator of nitrogen fixation. In this study, we for the first time reveal that GlnR of Paenibacillus polymyxa WLY78 is essentially required for nif gene transcription under nitrogen limitation, whereas both GlnR and glutamine synthetase (GS) encoded by glnA within glnRA operon are required for repressing nif expression under excess nitrogen. Dimerization of GlnR is necessary for binding of GlnR to DNA. GlnR in P. polymyxa WLY78 exists in a mixture of dimers and monomers. The C-terminal region of GlnR monomer is an autoinhibitory domain that prevents GlnR from binding DNA. Two GlnR-biding sites flank the -35/-10 regions of the nif promoter of the nif operon (nifBHDKENXhesAnifV). The GlnR-binding site Ⅰ (located upstream of -35/-10 regions of the nif promoter) is specially required for activating nif transcription, while GlnR-binding siteⅡ (located downstream of -35/-10 regions of the nif promoter) is for repressing nif expression. Under nitrogen limitation, GlnR dimer binds to GlnR-binding siteⅠ in a weak and transient association way and then activates nif transcription. During excess nitrogen, glutamine binds to and feedback inhibits GS by forming the complex FBI-GS. The FBI-GS interacts with the C-terminal domain of GlnR and stabilizes the binding affinity of GlnR to GlnR-binding site Ⅱ and thus represses nif transcription.

Dataset Information

Regulation of pyocin genes in Pseudomonas aeruginosa by positive (prtN) and negative (prtR) regulatory genes.

Publications

Regulation of pyocin genes in Pseudomonas aeruginosa by positive (prtN) and negative (prtR) regulatory genes.

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