The ferric iron uptake regulator (Fur) from the extreme acidophile Acidithiobacillus ferrooxidans

Microbiology ◽  
2005 ◽  
Vol 151 (6) ◽  
pp. 2005-2015 ◽  
Author(s):  
R. Quatrini ◽  
C. Lefimil ◽  
D. S. Holmes ◽  
E. Jedlicki
Keyword(s):  
Gene Expression ◽  
Stress Responses ◽  
Acidithiobacillus Ferrooxidans ◽  
Iron Uptake ◽  
Ferric Iron ◽  
Sequence Similarity ◽  
Cross Reactivity ◽  
Mobility Shift ◽  
E Coli ◽  
Protein Levels

Acidithiobacillus ferrooxidans is a Gram-negative bacterium that lives at pH 2 in high concentrations of soluble ferrous and ferric iron, making it an interesting model for understanding the biological mechanisms of bacterial iron uptake and homeostasis in extremely acid conditions. A candidate fur AF (Ferric Uptake Regulator) gene was identified in the A. ferrooxidans ATCC 23270 genome. FurAF has significant sequence similarity, including conservation of functional motifs, to known Fur orthologues and exhibits cross-reactivity to Escherichia coli Fur antiserum. The fur AF gene is able to complement fur deficiency in E. coli in an iron-responsive manner. FurAF is also able to bind specifically to E. coli Fur regulatory regions (Fur boxes) and to a candidate Fur box from A. ferrooxidans, as judged by electrophoretic mobility shift assays. FurAF represses gene expression from E. coli Fur-responsive promoters fiu and fhuF when expressed at high protein levels. However, it increases gene expression from these promoters at low concentrations and possibly from other Fur-regulated promoters involved in iron-responsive oxidative stress responses.

Ferric iron uptake genes are differentially expressed in the presence of copper sulfides in Acidithiobacillus ferrooxidans strain LR

2010 ◽  
Vol 99 (3) ◽  
pp. 609-617 ◽  
Author(s):  
Lúcio F. C. Ferraz ◽  
Leandro C. L. Verde ◽  
Renato Vicentini ◽  
Ana P. Felício ◽  
Marcelo L. Ribeiro ◽  
...  
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Iron Uptake ◽  
Ferric Iron ◽  
Differentially Expressed ◽  
Copper Sulfides

scholarly journals Complex Physiology and Compound Stress Responses during Fermentation of Alkali-Pretreated Corn Stover Hydrolysate by an Escherichia coli Ethanologen

2012 ◽  
Vol 78 (9) ◽  
pp. 3442-3457 ◽  
Author(s):  
Michael S. Schwalbach ◽  
David H. Keating ◽  
Mary Tremaine ◽  
Wesley D. Marner ◽  
Yaoping Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Amino Acids ◽  
Stationary Phase ◽  
Gene Expression Profiling ◽  
Stress Responses ◽  
Expression Profiling ◽  
Content Type ◽  
E Coli ◽  
Cell Maintenance

ABSTRACTThe physiology of ethanologenicEscherichia coligrown anaerobically in alkali-pretreated plant hydrolysates is complex and not well studied. To gain insight into howE. coliresponds to such hydrolysates, we studied anE. coliK-12 ethanologen fermenting a hydrolysate prepared from corn stover pretreated by ammonia fiber expansion. Despite the high sugar content (∼6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate,E. coliceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses during an exponential growth phase, a transition phase, and the glycolytically active stationary phase. During the exponential and transition phases, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate. However, after the majority of amino acids were depleted, the cells entered stationary phase, and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin, and ethanol stress collectively limits growth, sugar utilization rates, and ethanol yields in alkali-pretreated lignocellulosic hydrolysates.

scholarly journals HosA, a Member of the SlyA Family, Regulates Motility in Enteropathogenic Escherichia coli

2005 ◽  
Vol 73 (3) ◽  
pp. 1684-1694 ◽  
Author(s):  
Maria-José Ferrándiz ◽  
Keith Bishop ◽  
Paul Williams ◽  
Helen Withers
Keyword(s):  
Escherichia Coli ◽  
Transcriptional Regulators ◽  
Positive Control ◽  
Broth Culture ◽  
Wild Type ◽  
Mobility Shift ◽  
E Coli ◽  
Protein Levels ◽  
K 12 ◽  
Electrophoretic Mobility Shift Assays

ABSTRACT In enteropathogenic and enterohemorraghic Escherichia coli (EPEC and EHEC), two members of the SlyA family of transcriptional regulators have been identified as SlyA. Western blot analysis of the wild type and the corresponding hosA and slyA deletion mutants indicated that SlyA and HosA are distinct proteins whose expression is not interdependent. Of 27 different E. coli strains (EPEC, EHEC, enteroinvasive, enteroaggregative, uropathogenic, and commensal) examined, 14 were positive for both genes and proteins. To investigate hosA expression, a hosA::luxCDABE reporter gene fusion was constructed. hosA expression was significantly reduced in the hosA but not the slyA mutant and was influenced by temperature, salt, and pH. In contrast to SlyA, HosA did not activate the cryptic E. coli K-12 hemolysin ClyA. Mutation of hosA did not influence type III secretion, the regulation of the LEE1 and LEE4 operons, or the ability of E2348/69 to form attaching-and-effacing lesions on intestinal epithelial cells. HosA is, however, involved in the temperature-dependent positive control of motility on swim plates and regulates fliC expression and FliC protein levels. In electrophoretic mobility shift assays, purified HosA protein bound specifically to the fliC promoter, indicating that HosA directly modulates flagellin expression. While direct examination of flagellar structure and the motile behavior of individual hosA cells grown in broth culture at 30°C did not reveal any obvious differences, hosA mutants, unlike the wild type, clumped together, forming nonmotile aggregates which could account for the markedly reduced motility of the hosA mutant on swim plates at 30°C. We conclude that SlyA and HosA are independent transcriptional regulators that respond to different physicochemical cues to facilitate the environmental adaptation of E. coli.

scholarly journals Administration of capsule-selective endosialidase E minimizes upregulation of organ gene expression induced by experimental systemic infection with Escherichia coli K1

Microbiology ◽  
2010 ◽  
Vol 156 (7) ◽  
pp. 2205-2215 ◽  
Author(s):  
Andrea Zelmer ◽  
Melissa J. Martin ◽  
Ozan Gundogdu ◽  
George Birchenough ◽  
Rebecca Lever ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Stress Responses ◽  
Polysialic Acid ◽  
Newborn Infants ◽  
Systemic Infection ◽  
Bacterial Invasion ◽  
Neonatal Rats ◽  
Bacterial Surface ◽  
E Coli

Many neurotropic strains of Escherichia coli cause potentially lethal bacteraemia and meningitis in newborn infants by virtue of their capacity to elaborate the protective polysialic acid (polySia) K1 capsule. Recombinant capsule depolymerase, endosialidase E (endoE), selectively removes polySia from the bacterial surface; when administered intraperitoneally to infected neonatal rats, the enzyme interrupts the transit of E. coli K1 from gut to brain via the blood circulation and prevents death from systemic infection. We now show that experimental E. coli K1 infection is accompanied by extensive modulation of host gene expression in the liver, spleen and brain tissues of neonatal rats. Bacterial invasion of the brain resulted in a threefold or greater upregulation of approximately 400 genes, a large number of which were associated with the induction of inflammation and the immune and stress responses: these included genes encoding C–X–C and C–C chemokines, lipocalins, cytokines, apolipoproteins and enzymes involved in the synthesis of low-molecular-mass inflammatory mediators. Administration of a single dose of endoE, 24 h after initiation of systemic infection, markedly reduced, but did not completely abrogate, these changes in gene expression, suggesting that attenuation of E. coli K1 virulence by removal of the polySia capsule may minimize the attendant inflammatory processes that contribute to poor outcome in these severe systemic infections.

scholarly journals Transcriptional Activation of E2F1 Gene Expression by 17β-Estradiol in MCF-7 Cells Is Regulated by NF-Y-Sp1/Estrogen Receptor Interactions

1999 ◽  
Vol 13 (8) ◽  
pp. 1373-1387 ◽  
Author(s):  
Weili Wang ◽  
Lian Dong ◽  
Brad Saville ◽  
Stephen Safe
Keyword(s):  
Gene Expression ◽  
Estrogen Receptor ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Gene Promoter ◽  
Proximal Region ◽  
Mobility Shift ◽  
Protein Levels ◽  
17Β Estradiol ◽  
Mcf 7

Abstract 17β-Estradiol (E2) stimulated proliferation and DNA synthesis in MCF-7 human breast cancer cells, and this was accompanied by induction of E2F1 mRNA and protein levels. Analysis of the E2F1 gene promoter showed that the −146 to− 54 region was required for E2-responsiveness in transient transfection assays, and subsequent deletion/mutation analysis showed that a single upstream GC-rich and two downstream CCAAT-binding sites were required for transactivation by E2. Gel mobility shift assays with multiple oligonucleotides and protein antibodies (for supershifts) showed that the −146 to −54 region of the E2F1 gene promoter bound Sp1 and NF-Y proteins in MCF-7 cells. The estrogen receptor (ER) protein enhanced Sp1 interactions with upstream GC-rich sites, and interactions of ER, Sp1, and ER/Sp1 with downstream DNA bound-NF-Y was investigated by kinetic analysis for protein-DNA binding (on- and off-rates), coimmunoprecipitation, and pulldown assays using wild-type and truncated glutathione S-transferase (GST)-Sp1 chimeric proteins. The results showed that Sp1 protein enhanced the Bmax of NF-Y-DNA binding by more than 5-fold (on-rate); in addition, the Sp1-enhanced NF-Y-DNA complex was further stabilized by coincubation with ER and the rate of dissociation (t1/2) was decreased by approximately 50%. Sp1 antibodies immunoprecipitated [35S]NF-YA after coincubation with unlabeled Sp1 protein. Thus, transcriptional activation of E2F1 gene expression in MCF-7 cells by E2 is regulated by multiprotein ER/Sp1-NF-Y interactions at GC-rich and two CCAAT elements in the proximal region of the E2F1 gene promoter. This represents a unique trans-acting protein complex in which ligand-dependent transactivation by the ER is independent of direct ER interactions with promoter elements.

scholarly journals Anaerobic Sulfur Metabolism Coupled to Dissimilatory Iron Reduction in the Extremophile Acidithiobacillus ferrooxidans

2013 ◽  
Vol 79 (7) ◽  
pp. 2172-2181 ◽  
Author(s):  
Héctor Osorio ◽  
Stefanie Mangold ◽  
Yann Denis ◽  
Ivan Ñancucheo ◽  
Mario Esparza ◽  
...  
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Iron Reduction ◽  
Ferric Iron ◽  
Sulfur Metabolism ◽  
Anaerobic Growth ◽  
Anaerobic Conditions ◽  
Heterodisulfide Reductase ◽  
Content Type ◽  
Protein Levels

ABSTRACTGene transcription (microarrays) and protein levels (proteomics) were compared in cultures of the acidophilic chemolithotrophAcidithiobacillus ferrooxidansgrown on elemental sulfur as the electron donor under aerobic and anaerobic conditions, using either molecular oxygen or ferric iron as the electron acceptor, respectively. No evidence supporting the role of either tetrathionate hydrolase or arsenic reductase in mediating the transfer of electrons to ferric iron (as suggested by previous studies) was obtained. In addition, no novel ferric iron reductase was identified. However, data suggested that sulfur was disproportionated under anaerobic conditions, forming hydrogen sulfide via sulfur reductase and sulfate via heterodisulfide reductase and ATP sulfurylase. Supporting physiological evidence for H2S production came from the observation that soluble Cu2+included in anaerobically incubated cultures was precipitated (seemingly as CuS). Since H2S reduces ferric iron to ferrous in acidic medium, its production under anaerobic conditions indicates that anaerobic iron reduction is mediated, at least in part, by an indirect mechanism. Evidence was obtained for an alternative model implicating the transfer of electrons from S0to Fe3+via a respiratory chain that includes abc1complex and a cytochromec. Central carbon pathways were upregulated under aerobic conditions, correlating with higher growth rates, while many Calvin-Benson-Bassham cycle components were upregulated during anaerobic growth, probably as a result of more limited access to carbon dioxide. These results are important for understanding the role ofA. ferrooxidansin environmental biogeochemical metal cycling and in industrial bioleaching operations.

scholarly journals A shift to human body temperature (37°C) rapidly reprograms multiple adaptive responses in Escherichia coli that would facilitate niche survival and colonization

2021 ◽  
Author(s):  
Anastasia Gant Kanegusuku ◽  
Isidora N. Stankovic ◽  
Pamela A. Cote-Hammarlof ◽  
Priscilla H. Yong ◽  
Christine A. White-Ziegler
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Stress Response ◽  
Stress Responses ◽  
Anaerobic Respiration ◽  
Acid Resistance ◽  
Adaptive Responses ◽  
E Coli ◽  
Human Host ◽  
Small Regulatory Rnas

One of the first environmental cues sensed by a microbe as it enters a human host is an upshift in temperature to 37°C. In this dynamic timepoint analysis, we demonstrate that this environmental transition rapidly signals a multitude of gene expression changes in Escherichia coli . Bacteria grown at 23°C under aerobic conditions were shifted to 37°C and mRNA expression was measured at timepoints after the shift to 37°C (t=0.5, 1, and 4 hours). The first hour is characterized by a transient shift to anaerobic respiration strategies and stress responses, particularly acid resistance, indicating that temperature serves as a sentinel cue to predict and prepare for various niches within the host. The temperature effects on a subset of stress response genes were shown to be mediated by RpoS, directly correlated with RpoS, DsrA and RprA levels, and increased acid resistance was observed that was dependent on 23°C growth and RpoS. By 4 hours, gene expression shifted to aerobic respiration pathways, decreased stress responses, coupled with increases in genes associated with biosynthesis (amino acid, nucleotides), iron uptake, and host defense. ompT , a gene that confers resistance to antimicrobial peptides, was highly thermoregulated and with a pattern conserved in enteropathogenic and uropathogenic E. coli . An immediate decrease in curli gene expression concomitant with an increase in flagellar gene expression implicates temperature in this developmental decision. Together, our studies demonstrate that temperature signals a reprogramming of gene expression immediately upon an upshift that may predict, prepare, and benefit survival of the bacterium within the host. IMPORTANCE: As one of the first cues sensed by the microbe upon entry into a human host, understanding how bacteria like E. coli modulate gene expression in response to temperature improves our understanding of how bacteria immediately initiate responses beneficial to survival and colonization. For pathogens, understanding the various pathways of thermal regulation could yield valuable targets for anti-infective chemotherapeutic drugs or disinfection measures. In addition, our data provide a dynamic examination of the RpoS stress response, providing genome-wide support for how temperature impacts RpoS through changes in RpoS stability and modulation by small regulatory RNAs.

scholarly journals Characterization of a Novel Iron Acquisition Activity That Coordinates the Iron Response with Population Density under Iron-Replete Conditions in Bacillus subtilis

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Emily M. Roy ◽  
Kevin L. Griffith
Keyword(s):  
Bacillus Subtilis ◽  
Population Density ◽  
Iron Uptake ◽  
Ferric Iron ◽  
Iron Acquisition ◽  
Biological Processes ◽  
Aerobic Growth ◽  
Content Type ◽  
E Coli

ABSTRACT Iron is an essential micronutrient required for the viability of many organisms. Under oxidizing conditions, ferric iron is highly insoluble (∼10−9 to 10−18 M), yet bacteria typically require ∼10−6 M for survival. To overcome this disparity, many bacteria have adopted the use of extracellular iron-chelating siderophores coupled with specific iron-siderophore uptake systems. In the case of Bacillus subtilis, undomesticated strains produce the siderophore bacillibactin. However, many laboratory strains, e.g., JH642, have lost the ability to produce bacillibactin during the process of domestication. In this work, we identified a novel iron acquisition activity from strain JH642 that accumulates in the growth medium and coordinates the iron response with population density. The molecule(s) responsible for this activity was named elemental Fe(II/III) (Efe) acquisition factor because efeUOB (ywbLMN) is required for its activity. Unlike most iron uptake molecules, including siderophores and iron reductases, Efe acquisition factor is present under iron-replete conditions and is regulated independently of Fur repressor. Restoring bacillibactin production in strain JH642 inhibits the activity of Efe acquisition factor, presumably by sequestering available iron. A similar iron acquisition activity is produced from a mutant of Escherichia coli unable to synthesize the siderophore enterobactin. Given the conservation of efeUOB and its regulation by catecholic siderophores in B. subtilis and E. coli, we speculate that Efe acquisition factor is utilized by many bacteria, serves as an alternative to Fur-mediated iron acquisition systems, and provides cells with biologically available iron that would normally be inaccessible during aerobic growth under iron-replete conditions. IMPORTANCE Iron is an essential micronutrient required for a variety of biological processes, yet ferric iron is highly insoluble during aerobic growth. In this work, we identified a novel iron acquisition activity that coordinates the iron response with population density in laboratory strains of Bacillus subtilis. We named the molecule(s) responsible for this activity elemental Fe(II/III) (Efe) acquisition factor after the efeUOB (ywbLMN) operon required for its uptake into cells. Unlike most iron uptake systems, Efe acquisition factor is present under iron-replete conditions and is regulated independently of Fur, the master regulator of the iron response. We speculate that Efe acquisition factor is highly conserved among bacteria and serves as a backup to Fur-mediated iron acquisition systems.

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