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Series GSE45653 Query DataSets for GSE45653
Status Public on Aug 15, 2013
Title Iron stimulon and Fur regulon
Platform organism Caulobacter vibrioides CB15
Sample organism Caulobacter vibrioides NA1000
Experiment type Expression profiling by array
Summary 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
 
Overall design Two experimental procedures, each of them performed in two replicates. A total of four independent biological samples were used
 
Contributor(s) da Silva Neto JF, Lourenço RF, Marques MV
Citation(s) 23941329
Submission date Mar 31, 2013
Last update date Nov 14, 2013
Contact name Rogerio Lourenco
E-mail(s) lourenco@iq.usp.br
Organization name Universidade de Sao Paulo
Department Bioquimica
Street address Av. Prof. Lineu Prestes, 748
City Sao Paulo
State/province Sao Paulo
ZIP/Postal code 05508-900
Country Brazil
 
Platforms (1)
GPL10469 MIT Agilent Caulobacter 45K Array
Samples (4)
GSM1111325 WT iron x WT DP- rep1
GSM1111326 WT iron x WT DP- rep2
GSM1111327 WT iron x ∆fur iron- rep1
Relations
BioProject PRJNA195557

Download family Format
SOFT formatted family file(s) SOFTHelp
MINiML formatted family file(s) MINiMLHelp
Series Matrix File(s) TXTHelp

Supplementary file Size Download File type/resource
GSE45653_RAW.tar 17.5 Mb (http)(custom) TAR (of TXT)
Processed data included within Sample table
Processed data provided as supplementary file

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