Regulation of the<i>Helicobacter pylori</i>Fe-S Cluster Synthesis Protein NifS by Iron, Oxidative Stress Conditions, and Fur

Alamuri, Praveen; Mehta, Nalini; Burk, Andrew; Maier, Robert J.

doi:10.1128/jb.00104-06

Cited by 40 publications

(35 citation statements)

References 25 publications

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“…Specifically, stress-related Leptospirillum group II proteins more abundant in the laboratory biofilms included the iron-sulfur cluster assembly proteins, which form the center of many important redox active enzymes (Supplementary Table 5). It has been suggested that upregulation of the iron-sulfur cluster assembly operon occurs during periods of oxidative stress in response to free radical damage to the redox active sites of iron-sulfur proteins (Alamuri et al, 2006). Furthermore, a separate abundant oxidative stress protein in the laboratory sample, peptide methionine sulfoxide reductase, has been shown to have a direct role in protection from reactive oxygen species (Moskovitz et al, 1995).…”

Section: Acid Mine Drainage Chemoautotrophic Productionmentioning

confidence: 99%

Cultivation and quantitative proteomic analyses of acidophilic microbial communities

et al. 2009

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Acid mine drainage (AMD), an extreme environment characterized by low pH and high metal concentrations, can support dense acidophilic microbial biofilm communities that rely on chemoautotrophic production based on iron oxidation. Field determined production rates indicate that, despite the extreme conditions, these communities are sufficiently well adapted to their habitats to achieve primary production rates comparable to those of microbial communities occurring in some non-extreme environments. To enable laboratory studies of growth, production and ecology of AMD microbial communities, a culturing system was designed to reproduce natural biofilms, including organisms recalcitrant to cultivation. A comprehensive metabolic labeling-based quantitative proteomic analysis was used to verify that natural and laboratory communities were comparable at the functional level. Results confirmed that the composition and core metabolic activities of laboratory-grown communities were similar to a natural community, including the presence of active, low abundance bacteria and archaea that have not yet been isolated. However, laboratory growth rates were slow compared with natural communities, and this correlated with increased abundance of stress response proteins for the dominant bacteria in laboratory communities. Modification of cultivation conditions reduced the abundance of stress response proteins and increased laboratory community growth rates. The research presented here represents the first description of the application of a metabolic labeling-based quantitative proteomic analysis at the community level and resulted in a model microbial community system ideal for testing physiological and ecological hypotheses.

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Section: Acid Mine Drainage Chemoautotrophic Productionmentioning

confidence: 99%

Cultivation and quantitative proteomic analyses of acidophilic microbial communities

et al. 2009

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“…H. pylori responds and adapts to gastric stressors by altering gene expression through the use of transcriptional regulators. One such regulator, the ferric uptake regulator (Fur), is utilized to maintain iron homeostasis (4-6) but also to respond to pH (7)(8)(9), nitrosative, and oxidative stressors (10)(11)(12). Given the paucity of transcriptional regulators found in H. pylori compared to other bacterial organisms (13), it is perhaps not surprising that through the course of evolution, H. pylori Fur has taken on a more global role in gene regulation beyond iron uptake and storage.…”

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confidence: 99%

Identification and Characterization of Novel Helicobacter pylori apo-Fur-Regulated Target Genes

et al. 2013

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cIn Helicobacter pylori, the ferric uptake regulator (Fur) has evolved additional regulatory functions not seen in other bacteria; it can repress and activate different groups of genes in both its iron-bound and apo forms. Because little is understood about the process of apo-Fur repression and because only two apo-Fur-repressed genes (pfr and sodB) have previously been identified, we sought to expand our understanding of this type of regulation. Utilizing published genomic studies, we selected three potential new apo-Fur-regulated gene targets: serB, hydA, and the cytochrome c 553 gene. Transcriptional analyses confirmed Fur-dependent repression of these genes in the absence of iron, as well as derepression in the absence of Fur. Binding studies showed that apo-Fur directly interacted with the suspected hydA and cytochrome c 553 promoters but not that of serB, which was subsequently shown to be cotranscribed with pfr; apo-Fur-dependent regulation occurred at the pfr promoter. Alignments of apo-regulated promoter regions revealed a conserved, 6-bp consensus sequence (AAATGA). DNase I footprinting showed that this sequence lies within the protected regions of the pfr and hydA promoters. Moreover, mutation of the sequence in the pfr promoter abrogated Fur binding and DNase protection. Likewise, fluorescence anisotropy studies and binding studies with mutated consensus sequences showed that the sequence was important for apo-Fur binding to the pfr promoter. Together these studies expand the known apo-Fur regulon in H. pylori and characterize the first reported apo-Fur box sequence.

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“…In addition, it is also currently unclear whether apo-Fur functions as an oligomer (similar to Fe 2ϩ -Fur) or whether an alternative form of the protein is required for this type of regulation. Moreover, direct Fe 2ϩ -Fur-mediated activation has been demonstrated definitively for only one gene (nifS) in H. pylori, and the possible mechanisms underlying activation have not been determined (6). Given the distal location of the Fur binding sites in H. pylori Fe 2ϩ -Fur-activated promoters (6,197), it is not intuitively clear whether or not Fur would be able to interact directly with RNAP or whether another factor is involved in facilitating activation.…”

Section: Discussionmentioning

confidence: 99%

“…Detailed analysis of Fur regulation of the nifS promoter suggests that Fur can in fact act as a transcriptional activator. Under iron-replete conditions, Fur was found to protect two distinct regions within the nifS promoter (6). Although there are no clear Fur boxes in the nifS promoter, the Fur binding regions were reported to be 150 and 200 nucleotides upstream from the transcriptional start, which could be consistent with an orientation of Fur needed to activate transcription.…”

Section: Vol 75 2011 Variations In Mechanisms Of Epsilonproteobactementioning

confidence: 92%

“…Similar to Fur proteins in E. coli and C. jejuni, H. pylori Fur can act as a classic transcriptional repressor, utilizing iron as a cofactor (55). However, unlike Fur in other organisms, H. pylori Fur has also been shown to act as an apo-repressor as well as an activator (in both the iron-bound and apo forms) (6,118,128,130,161,197). Iron-bound Fur repression in H. pylori is similar to that seen in many other organisms: Fur is thought to bind to Fur boxes as a dimer and to repress transcription in an iron-dependent manner.…”

Section: Vol 75 2011 Variations In Mechanisms Of Epsilonproteobactementioning

confidence: 99%

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Change Is Good: Variations in Common Biological Mechanisms in the Epsilonproteobacterial GeneraCampylobacterandHelicobacter

Gilbreath

Cody

Merrell

et al. 2011

Microbiol Mol Biol Rev

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SUMMARY Microbial evolution and subsequent species diversification enable bacterial organisms to perform common biological processes by a variety of means. The epsilonproteobacteria are a diverse class of prokaryotes that thrive in diverse habitats. Many of these environmental niches are labeled as extreme, whereas other niches include various sites within human, animal, and insect hosts. Some epsilonproteobacteria, such as Campylobacter jejuni and Helicobacter pylori , are common pathogens of humans that inhabit specific regions of the gastrointestinal tract. As such, the biological processes of pathogenic Campylobacter and Helicobacter spp. are often modeled after those of common enteric pathogens such as Salmonella spp. and Escherichia coli . While many exquisite biological mechanisms involving biochemical processes, genetic regulatory pathways, and pathogenesis of disease have been elucidated from studies of Salmonella spp. and E. coli , these paradigms often do not apply to the same processes in the epsilonproteobacteria. Instead, these bacteria often display extensive variation in common biological mechanisms relative to those of other prototypical bacteria. In this review, five biological processes of commonly studied model bacterial species are compared to those of the epsilonproteobacteria C. jejuni and H. pylori . Distinct differences in the processes of flagellar biosynthesis, DNA uptake and recombination, iron homeostasis, interaction with epithelial cells, and protein glycosylation are highlighted. Collectively, these studies support a broader view of the vast repertoire of biological mechanisms employed by bacteria and suggest that future studies of the epsilonproteobacteria will continue to provide novel and interesting information regarding prokaryotic cellular biology.

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Regulation of theHelicobacter pyloriFe-S Cluster Synthesis Protein NifS by Iron, Oxidative Stress Conditions, and Fur

Cited by 40 publications

References 25 publications

Cultivation and quantitative proteomic analyses of acidophilic microbial communities

Cultivation and quantitative proteomic analyses of acidophilic microbial communities

Identification and Characterization of Novel Helicobacter pylori apo-Fur-Regulated Target Genes

Change Is Good: Variations in Common Biological Mechanisms in the Epsilonproteobacterial GeneraCampylobacterandHelicobacter

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