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The CgrA and CgrC proteins form a complex that positively regulates cupA fimbrial gene expression in Pseudomonas aeruginosa.

ABSTRACT: The CgrA and CgrC proteins of Pseudomonas aeruginosa are coregulators that are required for the phase-variable expression of the cupA fimbrial genes. Neither CgrA nor CgrC resembles a classical transcription regulator, and precisely how these proteins exert their regulatory effects on cupA gene expression is poorly understood. Here, we show that CgrA and CgrC interact with one another directly. We identify a mutant of CgrC that is specifically defective for interaction with CgrA and demonstrate that this mutant cannot restore the phase-variable expression of the cupA fimbrial genes to cells of a cgrC mutant strain. Using this mutant, we also show that CgrC associates with the cupA promoter regardless of whether or not it interacts with CgrA. Our findings establish that interaction between CgrA and CgrC is required for the phase-variable expression of the cupA fimbrial genes and suggest that CgrC exerts its regulatory effects directly at the cupA promoter, possibly by recruiting CgrA. Because the regions of CgrA and CgrC that we have identified as interacting with one another are highly conserved among orthologs, our findings raise the possibility that CgrA- and CgrC-related regulators present in other bacteria function coordinately through a direct protein-protein interaction.

SUBMITTER: McManus HR

PROVIDER: S-EPMC3209204 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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The CgrA and CgrC proteins form a complex that positively regulates cupA fimbrial gene expression in Pseudomonas aeruginosa.

McManus Heather R HR Dove Simon L SL

Journal of bacteriology 20110916 22

The CgrA and CgrC proteins of Pseudomonas aeruginosa are coregulators that are required for the phase-variable expression of the cupA fimbrial genes. Neither CgrA nor CgrC resembles a classical transcription regulator, and precisely how these proteins exert their regulatory effects on cupA gene expression is poorly understood. Here, we show that CgrA and CgrC interact with one another directly. We identify a mutant of CgrC that is specifically defective for interaction with CgrA and demonstrate ...[more]

PMID: 21926232

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Project description:BackgroundThe bacterium Pseudomonas aeruginosa is capable of three types of motilities: swimming, twitching and swarming. The latter is characterized by a fast and coordinated group movement over a semi-solid surface resulting from intercellular interactions and morphological differentiation. A striking feature of swarming motility is the complex fractal-like patterns displayed by migrating bacteria while they move away from their inoculation point. This type of group behaviour is still poorly understood and its characterization provides important information on bacterial structured communities such as biofilms. Using GeneChip® Affymetrix microarrays, we obtained the transcriptomic profiles of both bacterial populations located at the tip of migrating tendrils and swarm center of swarming colonies and compared these profiles to that of a bacterial control population grown on the same media but solidified to not allow swarming motility.ResultsMicroarray raw data were corrected for background noise with the RMA algorithm and quantile normalized. Differentially expressed genes between the three conditions were selected using a threshold of 1.5 log2-fold, which gave a total of 378 selected genes (6.3% of the predicted open reading frames of strain PA14). Major shifts in gene expression patterns are observed in each growth conditions, highlighting the presence of distinct bacterial subpopulations within a swarming colony (tendril tips vs. swarm center). Unexpectedly, microarrays expression data reveal that a minority of genes are up-regulated in tendril tip populations. Among them, we found energy metabolism, ribosomal protein and transport of small molecules related genes. On the other hand, many well-known virulence factors genes were globally repressed in tendril tip cells. Swarm center cells are distinct and appear to be under oxidative and copper stress responses.ConclusionsResults reported in this study show that, as opposed to swarm center cells, tendril tip populations of a swarming colony displays general down-regulation of genes associated with virulence and up-regulation of genes involved in energy metabolism. These results allow us to propose a model where tendril tip cells function as «scouts» whose main purpose is to rapidly spread on uncolonized surfaces while swarm center population are in a state allowing a permanent settlement of the colonized area (biofilm-like).

Dataset Information

The CgrA and CgrC proteins form a complex that positively regulates cupA fimbrial gene expression in Pseudomonas aeruginosa.

Publications

The CgrA and CgrC proteins form a complex that positively regulates cupA fimbrial gene expression in Pseudomonas aeruginosa.

Similar Datasets

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