Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptomic analysis of Vibrio vulnificus in response to iron concentration and Fur protein

ABSTRACT: V. vulnificus is a marine bacteria that causes diseases in both mammals and fish. In both hosts, the iron concentration represents a key factor that greatly influences the virulence of this bacterium. To further define the gene repertoire that is regulated by iron concentration and Fur protein (the main transcriptional regulator in response to iron concentration) in V. vulnificus, we obtained a mutant in Fur and used DNA microarray technology to monitor the expression of the entire gene repertoire in response to iron. Global transcriptomic response was reconstructed by comparing the transcriptional profiles of the wild-type (R99) and Fur mutant strains in poor and rich iron conditions. To identify the genes that were under control of Fur, we compared the transcriptomic profile of the wild-type strain with the profile of a mutant strain in Fur protein; in contrast, to identify the genes that were under control of iron, we compared the transcriptomic profile of the wild-type strain grown in iron-rich conditions with the profile of the wild-type strain grown in iron-restricted conditions. For each one of the four samples, three replicates were performed, and RNA was sampled in the mid-log phase of growth (wild-type, 6h; Fur mutant, 6h; wild-type+iron, 5h; wild-type-iron,9h).

ORGANISM(S): Vibrio vulnificus

SUBMITTER: David Pajuelo GM-CM-!mez

PROVIDER: E-GEOD-60553 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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

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Transcriptomic analysis of Vibrio vulnificus in response to iron concentration and Fur protein

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