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

Quatrini, Raquel; Lefimil, Claudia; Holmes, David S.; Jedlicki, Eugenia

doi:10.1099/mic.0.27581-0

Cited by 39 publications

(46 citation statements)

References 49 publications

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“…Levels of a-fur increase in cells during growth in sulfur medium (Fig. 4) that matches increases of Fur in cells grown in sulfur medium (Quatrini et al, 2005b). Conversely, levels of a-fur do not increase in cells grown in iron medium (Fig.…”

Section: Determination Of the Termination Of Transcription Of A-furmentioning

confidence: 86%

“…PCR products for cloning were purified from agarose gels with the SpinPrep gel DNA kit (Novagen). Oligonucleotide primers used in this study are listed in Table 2 and PCR conditions were as described previously (Quatrini et al, 2005b). A. ferrooxidans ATCC 23270 genomic DNA was used as a template to obtain PCR products for cloning.…”

Section: Methodsmentioning

confidence: 99%

“…Bacterial strains and plasmids are described in (Quatrini et al, 2005b). E. coli was grown at 37 uC in Luria broth (LB) with the pertinent antibiotics [ampicillin (Amp; 100 mg ml 21 ) and/or streptomycin (100 mg ml 21 )] as indicated in Table 1.…”

Section: Methodsmentioning

confidence: 99%

“…a-fur, an antisense RNA to fur in A. ferrooxidans sulfur medium versus in iron medium (Quatrini et al, 2005b), suggesting a post-transcriptional mechanism to regulate levels of Fur. Here, we extend this work by describing a cis-encoded antisense RNA to fur, termed a-fur RNA (Figs 1, 2 and 3), that is a candidate to carry out this regulation.…”

Section: Determination Of the Termination Of Transcription Of A-furmentioning

confidence: 99%

“…Its genome has been sequenced fully (Valdés et al, 2008). A gene encoding Fur and several target genes of Fur regulation, including those encoding iron storage proteins, other transporters and transcriptional factors, have been identified in A. ferrooxidans (Quatrini et al, 2005a, b;Osorio et al, 2008a).However, in contrast to other organisms in which Fur has been described, the environment of A. ferrooxidans is often rich in dissolved iron that can reach concentrations of 0.1 M at pH 2 due to the solubility of iron at low pH compared with its bioavailability under neutral aerobic conditions { [FeIII] Previous studies have determined that the levels of intracellular Fur in A. ferrooxidans vary with different growth conditions, in which higher levels of intracellular Fur were detected in A. ferrooxidans grown using sulfur versus iron as an energy source, without concomitant variations in fur mRNA levels (Quatrini et al, 2005b). One model to explain these results is that cellular levels of Fur could be regulated post-transcriptionally.…”

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confidence: 99%

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α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans

2014

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A large non-coding RNA, termed a-Fur, of~1000 nt has been detected in the extreme acidophile Acidithiobacillus ferrooxidans encoded on the antisense strand to the iron-responsive master regulator fur (ferric uptake regulator) gene. A promoter for a-fur was predicted bioinformatically and validated using gene fusion experiments. The promoter is situated within the coding region and in the same sense as proB, potentially encoding a glutamate 5-kinase. The 39 termination site of the a-fur transcript was determined by 39 rapid amplification of cDNA ends to lie 7 nt downstream of the start of transcription of fur. Thus, a-fur is antisense to the complete coding region of fur, including its predicted ribosome-binding site. The genetic context of a-fur is conserved in several members of the genus Acidithiobacillus but not in all acidophiles, indicating that it is monophyletic but not niche specific. It is hypothesized that a-Fur regulates the cellular level of Fur. This is the fourth example of an antisense RNA to fur, although it is the first in an extreme acidophile, and underscores the growing importance of cis-encoded non-coding RNAs as potential regulators involved in the microbial iron-responsive stimulon. INTRODUCTIONIron is an important micronutrient for micro-organisms because it is used as a cofactor for a large number of enzymes and electron transport proteins (Williams, 2012). However, it can also catalyse the Fenton reaction, generating hydroxyl radicals ( ? OH) that can damage many biological components, including DNA and proteins (Imlay, 2008;Cornelis et al., 2011). It is found at levels of~10 218 M (Andrews et al., 2003;Williams, 2012) in neutral, aerobic environments, which is far below the minimum requirement for bacterial growth (10 27 M) (Andrews et al., 2003). Consequently, micro-organisms have evolved complex systems for the uptake of iron, and have developed tight intracellular homeostatic controls to balance iron uptake and storage to avoid possible oxidative stress (Imlay, 2008;Cornelis et al., 2011). In many bacteria, this regulation is achieved by the action of the Fur (ferric uptake regulator) protein.In iron-rich conditions, Fur binds Fe 2+ (Mills & Marletta, 2005) and functions as a transcriptional repressor by binding to Fur boxes near promoter sequences blocking the entry of RNA polymerase, thus inhibiting initiation of RNA transcription. Genes regulated in this manner include those involved in the biosynthesis of siderophores and iron uptake (Friedman & O'Brian, 2003; Quatrini et al., 2007;Gao et al., 2008;Butcher et al., 2012), genes encoding small RNAs such as fsrA and ryhB (Smaldone et al., 2012;Massé & Gottesman, 2002;Salvail & Massé, 2012), and many other genes involved in iron homeostasis (reviewed by Salvail & Massé, 2012). Under iron-limiting conditions, Fur no longer binds Fe 2+ , reducing its affinity for Fur boxes and thus allowing transcription to proceed (Baichoo et al., 2002;Ochsner et al., 2002;Butcher et al., 2012). In the case of the siderophore and iron-uptake genes, t...

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Section: Determination Of the Termination Of Transcription Of A-furmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Determination Of the Termination Of Transcription Of A-furmentioning

confidence: 99%

mentioning

confidence: 99%

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α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans

2014

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Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

West²,

Banta³

2015

Biotech & Bioengineering

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The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has previously been genetically modified to produce isobutyric acid (IBA) from carbon dioxide while obtaining energy from the oxidation of ferrous iron. Here, a combinatorial approach was used to explore the influence of medium composition in both batch and chemostat cultures in order to improve IBA yields (g IBA/mol Fe(2+)) and productivities (g IBA/L/d). Medium pH, ferrous concentration (Fe(2+)), and inclusion of iron chelators all had positive impact on the IBA yield. In batch experiments, gluconate was found to be a superior iron chelator because its use resulted in smaller excursions in pH. In batch cultures, IBA yields decreased linearly with increases in the final effective Fe(3+) concentrations. Chemostat cultures followed similar trends as observed in batch cultures. Specific cellular productivities were found to be a function of the steady state ORP (Oxidation-reduction potential) of the growth medium, which is primarily determined by the Fe(3+) to Fe(2+) ratio. By operating at low ORP, chemostat cultures were able to achieve volumetric productivities as high as 3.8 ± 0.2 mg IBA/L/d which is a 14-fold increase over the previously reported value.

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Microbial Processing of Metal Sulfides

Donati¹,

Sand²

2007

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

Cited by 39 publications

References 49 publications

α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans

α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans

Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization

Microbial Processing of Metal Sulfides

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