Expression data from roots of Arabidopsis grown under sulfur, iron or potassium limitation
ABSTRACT: Deprivation of mineral nutrients causes significant retardation of plant growth. This slow growth is assumed to be associated with both nutrient specific transcriptional responses and additionally with common transcription patterns. In this study we adjusted the external supply of iron, potassium and sulfur to cause a similar retardation of growth. Global transcriptome analyses were performed to investigate whether the growth limitation by the different nutrient deficiencies triggered specific or similar transcriptional responses. The global transcriptome responded specifically to sulfur, iron or potassium deprivation. Arabidopsis thaliana plants were grown hydroponically under short-day conditions (8h light / 16h dark cycles) under full nutrient supply or under the limitation of sulfur, iron or potassium. Arabidopsis root material was harvested when the plants reached the age of 7 weeks (from sowing) and used for RNA extraction and hybridization on Affymetrix microarrays. Four biological replicates from each condition were analyzed.
Project description:High intracellular levels of unbound iron can contribute to the production of reactive oxygen species (ROS) in the Fenton reaction, while depletion of iron limits the availability of iron containing proteins, some of which have important functions in the oxidative stress defense. Vice versa increased ROS levels lead to damage of proteins with iron sulfur centers. Thus organisms have to coordinate and balance their responses to oxidative stress and iron availability. Our knowledge on the molecular mechanisms underlying the coregulation of these responses is still limited. To discriminate between a direct cellular response to iron limitation and indirect responses, which are the consequence of increased levels of ROS, we compared the response of the alpha proteobacterium Rhodobacter sphaeroides to iron limitation in presence or absence of oxygen. While some genes respond to iron limitation exclusively or much stronger in presence of oxygen, other genes show much stronger response in anaerobic conditions. Remarkably few genes show even opposite response to iron depletion in presence or absence of iron. RNA samples collected from anaerobically grown cultures in presence or absence of iron were analyzed by two-color microarrays
Project description:Transcriptional profiling of R. sphaeroides Δirr under iron limitation (-Fe) compared to control R. sphaeroides Δirr under normal growth conditions (+Fe). Two strain experiment under normal iron (+Fe) and iron limitation (-Fe) conditions. 6 Biological replicates, independently grown and harvested at OD660=0,4; 1-3 pooled in replicate 1, 4-6 pooled in replicate 2
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 Two experimental procedures, each of them performed in two replicates. A total of four independent biological samples were used
Project description:Iron is an essential cofactor for a wide range of cellular processes. Previous studies have shown that siderophore-mediated uptake and intracellular handling of iron are crucial for virulence of Aspergillus fumigatus. Here we show that the bzip-type transcription factor HapX plays a crucial role in the transcriptional remodeling required for adaption to iron starvation in this opportunistic fungal pathogen. HapX was found to be interconnected in a negative feed-back loop with the previously identified iron regulator SreA: SreA repressed expression of hapX during iron sufficiency and HapX repressed sreA during iron starvation. Genome-wide transcriptional profiling and analysis of selected metabolites (protophorphyrine IX, siderophores and amino acids) indicated extensive metabolic remodeling in response to iron starvation. HapX was found to participate in both, repression and activation of genes during iron starvation. HapX was in particular required for repression of iron-dependent and mitochondrial-localized activities including respiration, TCA cycle, amino acid metabolism, iron-sulfur-cluster biosynthesis and heme biosynthesis. Pathways positively affected by HapX included production of siderophores and the ribotoxin and major allergen AspF1. Analysis of the free amino acid pool revealed HapX-dependent coordination of the production of siderophores with the supply of its precursor ornithine. Consistent with the hapX expression pattern, HapX-deficiency was deleterious with respect to growth rate and conidiation during iron depleted but not iron-replete conditions. HapX-deficiency caused significant attenuation of virulence in a murine model aspergillosis underlining that A. fumigatus faces iron starvation in the host and that the HapX-dependent metabolic reprogramming is therefore crucial for virulence. A. fumigatus 293 and hapX mutants were grown in the presence and absence of iron and in cultures shifted from no iron to iron-containing conditions after 1 h incubation. Hybridizations were performed with biological replicates for wt vs hapX +/- iron. For the iron-shift experiments, there were biological replicates for wt in both conditions and for hapX in -iron but there was only a single biological sample for hapX iron-shift sample. All hybs were performed with flip-dye pairs.
Project description:B. pertussis Tohama I was cultivated in iron-depleted or iron-repleted medium in order to monitor proteins which are influence by iron supply. More than 200 proteins displayed increased or decreased levels. Proteins involved in iron acquisition, biofilm production and oxidative stress response were increased during iron starvation. Limited iron supply caused on the other hand decreased levels of virulence factors regulated by the BvgAS system.
Project description:All yeast strains used in this study (Table 1) are in the W303 background (ade2-1 can1-100, his3-1,15 leu2-3,112 trp1-1 ura3). For sulfur limitation microarray studies, WT, met4 delete, met31 delete met32 delete, cbf1 delete, and met28 delete strains were grown in minimal B-media [see Cherest, H., and Surdin-Kerjan, Y. (1992). Genetic analysis of a new mutation conferring cysteine auxotrophy in Saccharomyces cerevisiae: updating of the sulfur metabolism pathway. Genetics 130, p51-58 for B-media composition] supplemented with 0.5mM methionine as the sole sulfur source. An aliquot of cells was harvested for a t=0 time point while the remainder were filtered through a .22um Stericup filter (Millipore), then washed and resuspended in pre-warmed (30 C) B-media lacking any source of sulfur. Cells were harvested after 20, 40, and 80 minutes.
Project description:au15-01_iron-fit - fe-fit-diff_6d - Changes in gene expression profiles between fit knock-out, wild-type and FIT overexpressor seedlings under sufficient iron supply and under iron deficiency. - Col-0, HA-FIT and fit-3. 21 dye-swap - gene knock in (transgenic),gene knock out,treated vs untreated comparison
Project description:A. baumannii ATCC 17978 cells were incubated under iron replete (mueller-hinton) and iron limiting (MH + 200 µM 2,2'-dipyridyl) conditions, total RNA was extracted when cultures reached OD600=0.7. The probes on the microarray cover all predicted open reading frames (at least 4 per ORF) and additional replicates of housekeeping genes of the A. baumannii ATCC 17978 genome
Project description:A changing climate is altering many ocean properties that consequently will modify marine productivity. Previous phytoplankton manipulation studies have focused on individual or subsets of these properties. Here, we investigate the cumulative effects of multi-faceted change on a subantarctic diatom Pseudonitzschia multiseries by concurrently manipulating five stressors (light/nutrients/CO2/temperature/iron) that primarily control its physiology, and explore underlying reasons for altered physiological performance. Climate change enhances diatom growth mainly owing to warming and iron enrichment, and both properties decrease cellular nutrient quotas, partially offsetting any effects of decreased nutrient supply by 2100. Physiological diagnostics and comparative proteomics demonstrate the joint importance of individual and interactive effects of temperature and iron, and reveal biased future predictions from experimental outcomes when only a subset of multi-stressors is considered. Our findings for subantarctic waters illustrate how composite regional studies are needed to provide accurate global projections of future shifts in productivity and distinguish underlying species-specific physiological mechanisms.
Project description:Abstract: The crenarchaeal order Sulfolobales collectively contains at least five major terminal oxidase complexes. Based on genome sequence information, all five complexes are found only in Metallosphaera sedula and Sulfolobus tokodaii, the two sequenced Sulfolobales capable of iron oxidization. While specific respiratory complexes in certain Sulfolobales have been characterized previously as proton pumps for maintaining intracellular pH and generating proton motive force (pmf), their contribution to sulfur and iron biooxidation has not been considered. For M. sedula growing in the presence of ferrous iron and reduced inorganic sulfur compounds (RISCs), global transcriptional analysis was used to track the response of specific genes associated with these complexes, as well as other known and putative respiratory electron transport chain elements. ORFs from all five terminal oxidase or bc1-like complexes were stimulated on one or more conditions tested. Components of the fox (Msed0467-0489) and soxNL-cbsABA (Msed0500-0505) terminal/quinol oxidase clusters were triggered by ferrous iron, while the soxABCDD' terminal oxidase cluster (Msed0285-0291) were induced by tetrathionate and S°. Chemolithotrophic electron transport elements, including a putative tetrathionate hydrolase (Msed0804), a novel polysulfide/sulfur/DMSO reductase-like complex (Msed0812-0818), and a novel heterodisulfide reductase-like complex (Msed1542-1550), were also stimulated by RISCs. Furthermore, several hypothetical proteins were found to have strong responses to ferrous iron or RISCs, suggesting additional candidates in iron or sulfur oxidation-related pathways. From this analysis, a comprehensive model for electron transport in M. sedula could be proposed as the basis for examining specific details of iron and sulfur oxidation in this bioleaching archaeon. Overall design: 5-slide loop of Mse cells includes 5 conditions tested: yeast exact (Y), yeast extract + ferrous sulfate (YFS), yeast extract + potassium sulfate (YKS), yeast extract + potassium tetrathionate (YKT), and yeast extract + elemental sulfur (YS). Half of an RNA sample for one condition was labeled with Cy3 while the other half was labeled with Cy5. The two differently labeled samples were run on different slides. Each probe is spotted on each slide 5 times (5 replicates; spot intensities for all replicates on slide provided in associated raw data file).