Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

PhyK, PhyR, σT and σU regulons

ABSTRACT: The extracytoplasmic function sigma factor σT is the master regulator of general stress response in Caulobacter crescentus, and controls the expression of its paralogue σU. This work showed that PhyR and NepR act as positive and negative regulators, respectively, of σT expression and function. Biochemical data also indicated that NepR directly binds σT and the phosphorylated form of PhyR. We also demonstrated the essential role of the histidine kinase gene CC3474, here denominated phyK, for expression of σT-dependent genes and for resistance to stress conditions. Additionally, in vivo evidence of PhyK-dependent phosphorylation of PhyR is presented. This study also identified a conserved cysteine residue (C95) present in the periplasmic portion of PhyK that is crucial for the function of the protein. Furthermore, we showed that PhyK, PhyR and σT regulate the same set of genes and that σT is apparently responsible for the direct control of its complete regulon. In contrast, σU seems to have a very modest contribution for expression of a subset of σT-dependent genes. In conclusion, this work describes the mechanism involved in the control of general stress response in C. crescentus. Five experimetal procedures, each of them performed in three replicates. A total of fifteen independent biological samples were used

ORGANISM(S): Caulobacter crescentus NA1000

SUBMITTER: Rogerio Lourenco

PROVIDER: E-GEOD-26977 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

A two-component system, an anti-sigma factor and two paralogous ECF sigma factors are involved in the control of general stress response in Caulobacter crescentus.

Lourenço Rogério F RF Kohler Christian C Gomes Suely L SL

Molecular microbiology 20110512 6

The extracytoplasmic function sigma factor σ(T) is the master regulator of general stress response in Caulobacter crescentus and controls the expression of its paralogue σ(U). In this work we showed that PhyR and NepR act, respectively, as positive and negative regulators of σ(T) expression and function. Biochemical data also demonstrated that NepR directly binds σ(T) and the phosphorylated form of PhyR. We also described the essential role of the histidine kinase gene CC3474, here denominated p ...[more]

PMID: 21564331

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Project description:In the alpha subclass of proteobacteria iron homeostasis is controlled by diverse iron responsive regulators. Caulobacter crescentus, an important freshwater Î±-proteobacterium, uses the ferric uptake repressor (Fur) for such purpose. However, the impact of the iron availability on the C. crescentus transcriptome and an overall perspective of the regulatory networks involved remain unknown. In this work we report the identification of iron-responsive and Fur-regulated genes in C. crescentus using microarray-based global transcriptional analyses. We identify 46 genes that were strongly upregulated both by mutation of fur and by iron limitation condition. Among them, there are genes involved in iron uptake (four TonB dependent receptor gene clusters, feoAB), riboflavin biosynthesis and some genes encoding hypothetical proteins. Most of these genes are associated with Fur binding sites, implicating them as direct targets of Fur-mediated repression. These data were validated by Î²-galactosidase and EMSA assays for two operons encoding putative transporters. The role of Fur as a positive regulator is also evident, given that 50 genes were downregulated both by mutation of fur and under low-iron condition. As expected, this group includes many genes involved in energy metabolism, mostly iron-using enzymes. Surprisingly, are also included in this group many genes encoding TonB dependent receptors and the genes fixK, fixT and ftrB encoding an oxygen signaling network required for growth during hypoxia. Bioinformatics analyses performed in the promoters of these genes suggest that positive regulation by Fur is mainly indirect. In addition to the Fur modulon, iron limitation altered expression of more 103 genes, including upregulation of genes involved in Fe-S cluster assembly, oxidative stress and heat shock response, as well as downregulation of genes implicated in amino acid metabolism, chemotaxis and motility. Altogether, our results showed that adaptation of C. crescentus to iron limitation involves increasing the transcription of iron-acquisition systems and decreasing the production of iron-using proteins as a general strategy Two experimental procedures, each of them performed in two replicates. A total of four independent biological samples were used

Project description:In the alpha subclass of proteobacteria iron homeostasis is controlled by diverse iron responsive regulators. Caulobacter crescentus, an important freshwater α-proteobacterium, uses the ferric uptake repressor (Fur) for such purpose. However, the impact of the iron availability on the C. crescentus transcriptome and an overall perspective of the regulatory networks involved remain unknown. In this work we report the identification of iron-responsive and Fur-regulated genes in C. crescentus using microarray-based global transcriptional analyses. We identify 46 genes that were strongly upregulated both by mutation of fur and by iron limitation condition. Among them, there are genes involved in iron uptake (four TonB dependent receptor gene clusters, feoAB), riboflavin biosynthesis and some genes encoding hypothetical proteins. Most of these genes are associated with Fur binding sites, implicating them as direct targets of Fur-mediated repression. These data were validated by β-galactosidase and EMSA assays for two operons encoding putative transporters. The role of Fur as a positive regulator is also evident, given that 50 genes were downregulated both by mutation of fur and under low-iron condition. As expected, this group includes many genes involved in energy metabolism, mostly iron-using enzymes. Surprisingly, are also included in this group many genes encoding TonB dependent receptors and the genes fixK, fixT and ftrB encoding an oxygen signaling network required for growth during hypoxia. Bioinformatics analyses performed in the promoters of these genes suggest that positive regulation by Fur is mainly indirect. In addition to the Fur modulon, iron limitation altered expression of more 103 genes, including upregulation of genes involved in Fe-S cluster assembly, oxidative stress and heat shock response, as well as downregulation of genes implicated in amino acid metabolism, chemotaxis and motility. Altogether, our results showed that adaptation of C. crescentus to iron limitation involves increasing the transcription of iron-acquisition systems and decreasing the production of iron-using proteins as a general strategy

Dataset Information

PhyK, PhyR, σT and σU regulons

Publications

A two-component system, an anti-sigma factor and two paralogous ECF sigma factors are involved in the control of general stress response in Caulobacter crescentus.

Similar Datasets

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