Characterization of the ferrioxamine uptake system of Nitrosomonas europaea

Wei, Xueming; Sayavedra-Soto, Luis A.; Arp, Daniel J.

doi:10.1099/mic.0.2007/010603-0

Cited by 7 publications

(7 citation statements)

References 47 publications

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“…N. europaea can use the siderophore ferrioxamine for its iron uptake after a 3 to 4 day lag period suggesting that the ferrioxamine uptake system in N. europaea requires induction [13,14]. When N. europaea fur:kanP mutant was grown in Fe-limiting media containing ferrioxamine, there was no lag phase (Figure 5B) indicating that the ferrioxamine uptake system was already induced in the fur:kanP mutant.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have shown that N. europaea grown in Fe-limited medium stimulated expression of several Fe-regulated outer membrane proteins (TonB-dependent receptors) with molecular masses of ~ 80 kDa [13,14]. To determine whether the expression of these proteins was regulated by fur , the N. europaea wild type and the fur: kanP mutant strains were cultured in Fe-replete and Fe-limited media and their total outer membrane proteins were isolated.…”

Section: Resultsmentioning

confidence: 99%

“…N. europaea's inability to produce siderophores in Fe-replete or Fe-limited media was further confirmed by universal Chrome Azurol S assay [12]. N. europaea responds to iron limitation by elevating production of Fe 3+ -siderophore receptors normally repressed under iron-replete conditions [13,14]. Several N. europaea iron-repressible genes contain sequences similar to the E. coli Fur box (unpublished data) in their promoter regions; hence it is likely that a Fur-like repressor regulates iron uptake genes in N. europaea as well.…”

Section: Introductionmentioning

confidence: 99%

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Role of a Fur homolog in iron metabolism in Nitrosomonas europaea

et al. 2011

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BackgroundIn response to environmental iron concentrations, many bacteria coordinately regulate transcription of genes involved in iron acquisition via the ferric uptake regulation (Fur) system. The genome of Nitrosomonas europaea, an ammonia-oxidizing bacterium, carries three genes (NE0616, NE0730 and NE1722) encoding proteins belonging to Fur family.ResultsOf the three N. europaea fur homologs, only the Fur homolog encoded by gene NE0616 complemented the Escherichia coli H1780 fur mutant. A N. europaea fur:kanP mutant strain was created by insertion of kanamycin-resistance cassette in the promoter region of NE0616 fur homolog. The total cellular iron contents of the fur:kanP mutant strain increased by 1.5-fold compared to wild type when grown in Fe-replete media. Relative to the wild type, the fur:kanP mutant exhibited increased sensitivity to iron at or above 500 μM concentrations. Unlike the wild type, the fur:kanP mutant was capable of utilizing iron-bound ferrioxamine without any lag phase and showed over expression of several outer membrane TonB-dependent receptor proteins irrespective of Fe availability.ConclusionsOur studies have clearly indicated a role in Fe regulation by the Fur protein encoded by N. europaea NE0616 gene. Additional studies are required to fully delineate role of this fur homolog.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of a Fur homolog in iron metabolism in Nitrosomonas europaea

et al. 2011

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“…The water-soluble bacterial protein synthesis inhibitors neomycin, kanamycin, and gentamicin were utilized. Kanamycin and gentamicin have been proven effective in preventing the growth of the AOB Nitrosomonas europaea (13,21,56). The effects of the water-soluble eukaryotic protein synthesis inhibitors emetine and cycloheximide were evaluated.…”

Section: Chemicalsmentioning

confidence: 99%

Evidence for Different Contributions of Archaea and Bacteria to the Ammonia-Oxidizing Potential of Diverse Oregon Soils

Taylor

Zeglin

Dooley

et al. 2010

Appl Environ Microbiol

133

100

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A method was developed to determine the contributions of ammonia-oxidizing archaea (AOA) and ammoniaoxidizing bacteria (AOB) to the nitrification potentials (NPs) of soils taken from forest, pasture, cropped, and fallowed (19 years) lands. Soil slurries were exposed to acetylene to irreversibly inactivate ammonia monooxygenase, and upon the removal of acetylene, the recovery of nitrification potential (RNP) was monitored in the presence and absence of bacterial or eukaryotic protein synthesis inhibitors. For unknown reasons, and despite measureable NPs, RNP did not occur consistently in forest soil samples; however, pasture, cropped, and fallowed soil RNPs commenced after lags that ranged from 12 to 30 h after acetylene removal. Cropped soil RNP was completely prevented by the bacterial protein synthesis inhibitor kanamycin (800 g/ml), whereas a combination of kanamycin plus gentamicin (800 g/ml each) only partially prevented the RNP (60%) of fallowed soils. Pasture soil RNP was completely insensitive to either kanamycin, gentamicin, or a combination of the two. Unlike cropped soil, pasture and fallowed soil RNPs occurred at both 30°C and 40°C and without supplemental NH 4 ؉ (<10 M NH 4 ؉ in solution), and pasture soil RNP demonstrated ϳ50% insensitivity to 100 M allyl thiourea (ATU). In addition, fallowed and pasture soil RNPs were insensitive to the fungal inhibitors nystatin and azoxystrobin. This combination of properties suggests that neither fungi nor AOB contributed to pasture soil RNP and that AOA were responsible for the RNP of the pasture soils. Both AOA and AOB may contribute to RNP in fallowed soil, while RNP in cropped soils was dominated by AOB.Until 2005 the majority of ammonia (NH 3 ) oxidation in natural environments was thought to be carried out by a phylogenetically distinct group of NH 3 -oxidizing bacteria (AOB). This nitrification paradigm was challenged by reports that thaumarchaeota carry the genes that encode the enzyme ammonia monooxygenase (AMO) (55); the isolation of "Candidatus Nitrosopumilus maritimus" strain SCM1, an obligate autotrophic thaumarchaeal NH 3 oxidizer (35); the detection of archaeal amoA gene transcripts in soil (54, 55); and the realization that ammonia-oxidizing archaea (AOA) were widely distributed (19) and often more numerous than AOB in soil (36), marine (40), and hot spring (52, 57) ecosystems. Others have correlated either the AOA (7,46,58) or AOB amoA gene copy abundance (17, 32) with nitrification activity and detected the expression of AOA amoA mRNA (43, 60). To our knowledge there is no published work that has directly distinguished NH 3 -oxidizing activity by AOA from NH 3 -oxidizing activity by AOB in soils.As yet, it is unknown what factors determine whether AOA or AOB nitrify in an environment. We hypothesized that AOA and AOB might contribute differentially to nitrification in diverse soils across a landscape with different physical and chemical characteristics, plant community compositions, and management practices. We know that nitrification by AOA a...

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“…The glassware, iron-replete, iron-limited, and irondepleted media used in this study are prepared as described (Wei et al 2006(Wei et al , 2007Vajrala et al 2010Vajrala et al , 2011. Lyophilized hemoglobin from bovine blood was purchased from Sigma.…”

Section: Bacterial Culture and Treatmentsmentioning

confidence: 99%

Global analysis of the Nitrosomonas europaea iron starvation stimulon

et al. 2011

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The importance of iron to the metabolism of the ammonia-oxidizing bacterium Nitrosomonas europaea is well known. However, the mechanisms by which N. europaea acquires iron under iron limitation are less well known. To obtain insight into these mechanisms, transcriptional profiling of N. europaea was performed during growth under different iron availabilities. Of 2,355 N. europaea genes on DNA microarrays, transcripts for 247 genes were identified as differentially expressed when cells were grown under iron limitation compared to cells grown under iron-replete conditions. Genes with higher transcript levels in response to iron limitation included those with confirmed or assigned roles in iron acquisition. Genes with lower transcript levels included those encoding iron-containing proteins. Our analysis identified several potentially novel iron acquisition systems in N. europaea and provided support for the primary involvement of a TonB-dependent heme receptor gene in N. europaea iron homeostasis. We demonstrated that hemoglobin can act as an iron source under iron-depleted conditions for N. europaea. In addition, we identified a hypothetical protein carrying a lipocalin-like domain that may have the ability to chelate iron for growth in iron-limited media.

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Characterization of the ferrioxamine uptake system of Nitrosomonas europaea

Cited by 7 publications

References 47 publications

Role of a Fur homolog in iron metabolism in Nitrosomonas europaea

Role of a Fur homolog in iron metabolism in Nitrosomonas europaea

Evidence for Different Contributions of Archaea and Bacteria to the Ammonia-Oxidizing Potential of Diverse Oregon Soils

Global analysis of the Nitrosomonas europaea iron starvation stimulon

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