The Dps4 from Nostoc punctiforme ATCC 29133 is a member of His-type FOC containing Dps protein class that can be broadly found among cyanobacteria

AbstractDps proteins (DNA-binding proteins from starved cells) have been found to detoxify H2O2. At their catalytic centers, the ferroxidase center (FOC), Dps proteins utilize Fe2+ to reduce H2O2 and therefore play an essential role in the protection against oxidative stress and maintaining iron homeostasis. Whereas most bacteria accommodate one or two Dps, there are five different Dps proteins in Nostoc punctiforme, a phototrophic and filamentous cyanobacterium. This uncommonly high number of Dps proteins implies a sophisticated machinery for maintaining complex iron homeostasis and for protection against oxidative stress. Functional analyses and structural information on cyanobacterial Dps proteins are rare, but essential for understanding the function of each of the NpDps proteins. In this study, we present the crystal structure of NpDps4 in its metal-free, iron- and zinc-bound forms. The FOC coordinates either two iron atoms or one zinc atom. Spectroscopic analyses revealed that NpDps4 could oxidize Fe2+ utilizing O2, but no evidence for its use of the oxidant H2O2 could be found. We identified Zn2+ to be an effective inhibitor of the O2-mediated Fe2+ oxidation in NpDps4. NpDps4 exhibits a FOC that is very different from canonical Dps, but structurally similar to the atypical one from DpsA of Thermosynechococcus elongatus. Sequence comparisons among Dps protein homologs to NpDps4 within the cyanobacterial phylum led us to classify a novel FOC class: the His-type FOC. The features of this special FOC have not been identified in Dps proteins from other bacterial phyla and it might be unique to cyanobacterial Dps proteins.

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Glutaredoxins Grx4 and Grx3 of Saccharomyces cerevisiae Play a Role in Actin Dynamics through Their Trx Domains, Which Contributes to Oxidative Stress Resistance

Applied and Environmental Microbiology ◽

10.1128/aem.01755-10 ◽

2010 ◽

Vol 76 (23) ◽

pp. 7826-7835 ◽

Cited By ~ 29

Author(s):

Nuria Pujol-Carrion ◽

Maria Angeles de la Torre-Ruiz

Keyword(s):

Oxidative Stress ◽

Saccharomyces Cerevisiae ◽

Actin Cytoskeleton ◽

Iron Homeostasis ◽

Actin Dynamics ◽

Actin Cable ◽

Ros Accumulation ◽

Cytoskeleton Remodeling ◽

Cellular Defenses ◽

Functional Analyses

ABSTRACT Grx3 and Grx4 are two monothiol glutaredoxins of Saccharomyces cerevisiae that have previously been characterized as regulators of Aft1 localization and therefore of iron homeostasis. In this study, we present data showing that both Grx3 and Grx4 have new roles in actin cytoskeleton remodeling and in cellular defenses against oxidative stress caused by reactive oxygen species (ROS) accumulation. The Grx4 protein plays a unique role in the maintenance of actin cable integrity, which is independent of its role in the transcriptional regulation of Aft1. Grx3 plays an additive and redundant role, in combination with Grx4, in the organization of the actin cytoskeleton, both under normal conditions and in response to external oxidative stress. Each Grx3 and Grx4 protein contains a thioredoxin domain sequence (Trx), followed by a glutaredoxin domain (Grx). We performed functional analyses of each of the two domains and characterized different functions for them. Each of the two Grx domains plays a role in ROS detoxification and cell viability. However, the Trx domain of each Grx4 and Grx3 protein acts independently of its respective Grx domain in a novel function that involves the polarization of the actin cytoskeleton, which also determines cell resistance against oxidative conditions. Finally, we present experimental evidence demonstrating that Grx4 behaves as an antioxidant protein increasing cell survival under conditions of oxidative stress.

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Role of hepcidin in oxidative stress and cell death of cultured mouse renal collecting duct cells: protection against iron and sensitization to cadmium

Archives of Toxicology ◽

10.1007/s00204-021-03106-z ◽

2021 ◽

Author(s):

Stephanie Probst ◽

Johannes Fels ◽

Bettina Scharner ◽

Natascha A. Wolff ◽

Eleni Roussa ◽

...

Keyword(s):

Oxidative Stress ◽

Cell Death ◽

Cell Fate ◽

Catalase Activity ◽

Metal Ion ◽

Iron Homeostasis ◽

Collecting Duct ◽

Duct Cell ◽

Plasmid Transfection

AbstractThe liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5–5 μmol/l) and/or Fe2+ (50–100 μmol/l) for 4–24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.

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Fur controls iron homeostasis and oxidative stress defense in the oligotrophic alpha-proteobacterium Caulobacter crescentus

Nucleic Acids Research ◽

10.1093/nar/gkp509 ◽

2009 ◽

Vol 37 (14) ◽

pp. 4812-4825 ◽

Cited By ~ 40

Author(s):

José F. da Silva Neto ◽

Vânia S. Braz ◽

Valéria C. S. Italiani ◽

Marilis V. Marques

Keyword(s):

Oxidative Stress ◽

Iron Homeostasis ◽

Caulobacter Crescentus ◽

Oxidative Stress Defense ◽

And Oxidative Stress ◽

Stress Defense

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DR1440 is a potential iron efflux protein involved in maintenance of iron homeostasis and resistance of Deinococcus radiodurans to oxidative stress

PLoS ONE ◽

10.1371/journal.pone.0202287 ◽

2018 ◽

Vol 13 (8) ◽

pp. e0202287 ◽

Cited By ~ 4

Author(s):

Shang Dai ◽

Ye Jin ◽

Tao Li ◽

Yulan Weng ◽

Xiaolin Xu ◽

...

Keyword(s):

Oxidative Stress ◽

Iron Homeostasis ◽

Deinococcus Radiodurans

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The dps Gene of Symbiotic “Candidatus Legionella jeonii” in Amoeba proteus Responds to Hydrogen Peroxide and Phagocytosis

Journal of Bacteriology ◽

10.1128/jb.00576-06 ◽

2006 ◽

Vol 188 (21) ◽

pp. 7572-7580 ◽

Cited By ~ 12

Author(s):

Miey Park ◽

Seong Tae Yun ◽

Sue-Yun Hwang ◽

Choong-Ill Chun ◽

Tae In Ahn

Keyword(s):

Oxidative Stress ◽

Hydrogen Peroxide ◽

Host Cell ◽

Genomic Library ◽

Amoeba Proteus ◽

Host Cells ◽

Intracellular Pathogens ◽

Protective Mechanisms ◽

Dps Protein ◽

Cloned Gene

ABSTRACT To survive in host cells, intracellular pathogens or symbiotic bacteria require protective mechanisms to overcome the oxidative stress generated by phagocytic activities of the host. By genomic library tagging, we cloned a dps (stands for DNA-binding protein from starved cells) gene of the symbiotic “Candidatus Legionella jeonii” organism (called the X bacterium) (dps X) that grows in Amoeba proteus. The gene encodes a 17-kDa protein (pI 5.19) with 91% homology to Dps and DNA-binding ferritin-like proteins of other organisms. The cloned gene complemented the dps mutant of Escherichia coli and conferred resistance to hydrogen peroxide. DpsX proteins purified from E. coli transformed with the dps X gene were in oligomeric form, formed a complex with pBlueskript SKII DNA, and protected the DNA from DNase I digestion and H2O2-mediated damage. The expression of the dps X gene in “Candidatus Legionella jeonii” was enhanced when the host amoeba was treated with 2 mM H2O2 and by phagocytic activities of the host cell. These results suggested that the Dps protein has a function protective of the bacterial DNA and that its gene expression responds to oxidative stress generated by phagocytic activities of the host cell. With regard to the fact that invasion of Legionella sp. into respiratory phagocytic cells causes pneumonia in mammals, further characterization of dps X expression in the Legionella sp. that multiplies in a protozoan host in the natural environment may provide valuable information toward understanding the protective mechanisms of intracellular pathogens.

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Variability of the Transferrin Receptor 2 Gene in AMD

Disease Markers ◽

10.1155/2014/507356 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Daniel Wysokinski ◽

Janusz Blasiak ◽

Mariola Dorecka ◽

Marta Kowalska ◽

Jacek Robaszkiewicz ◽

...

Keyword(s):

Oxidative Stress ◽

Risk Factors ◽

Transferrin Receptor ◽

Fenton Reaction ◽

Iron Homeostasis ◽

Critical Role ◽

Age Related Macular Degeneration ◽

Age Related ◽

Its Gene ◽

Transferrin Receptor 2

Oxidative stress is a major factor in the pathogenesis of age-related macular degeneration (AMD). Iron may catalyze the Fenton reaction resulting in overproduction of reactive oxygen species. Transferrin receptor 2 plays a critical role in iron homeostasis and variability in its gene may influence oxidative stress and AMD occurrence. To verify this hypothesis we assessed the association between polymorphisms of theTFR2gene and AMD. A total of 493 AMD patients and 171 matched controls were genotyped for the two polymorphisms of theTFR2gene: c.1892C>T (rs2075674) and c.−258+123T>C (rs4434553). We also assessed the modulation of some AMD risk factors by these polymorphisms. The CC and TT genotypes of the c.1892C>T were associated with AMD occurrence but the latter only in obese patients. The other polymorphism was not associated with AMD occurrence, but the CC genotype was correlated with an increasing AMD frequency in subjects withBMI<26. The TT genotype and the T allele of this polymorphism decreased AMD occurrence in subjects above 72 years, whereas the TC genotype and the C allele increased occurrence of AMD in this group. The c.1892C>T and c.−258+123T>C polymorphisms of theTRF2gene may be associated with AMD occurrence, either directly or by modulation of risk factors.

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Polymorphism of the Transferrin Gene in Eye Diseases: Keratoconus and Fuchs Endothelial Corneal Dystrophy

BioMed Research International ◽

10.1155/2013/247438 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Katarzyna A. Wójcik ◽

Ewelina Synowiec ◽

Manuel P. Jiménez-García ◽

Anna Kaminska ◽

Piotr Polakowski ◽

...

Keyword(s):

Oxidative Stress ◽

Risk Factors ◽

Fenton Reaction ◽

Iron Homeostasis ◽

Corneal Dystrophy ◽

Eye Diseases ◽

Blood Lymphocytes ◽

Its Gene ◽

Pcr Rflp ◽

Transferrin Gene

Oxidative stress may play a role in the pathogenesis of keratoconus (KC) and Fuchs endothelial corneal dystrophy (FECD). Iron may promote the stress by the Fenton reaction, so its homeostasis should be strictly controlled. Transferrin is essential for iron homeostasis because it transports iron from plasma into cells. The malfunction of transferrin, which may be caused by variation in its gene (TF) variation, may contribute to oxidative stress and change KC and FECD risk. To verify this hypothesis we investigated the association between three polymorphisms of theTFgene, g.3296G>A (rs8177178), g.3481A>G (rs8177179), and c.–2G>A (rs1130459), and KC and FECD occurrence. Genotyping was performed in blood lymphocytes in 216 patients with KC, 130 patients with FECD and 228 controls by PCR-RFLP. We studied also the influence of other risk factors. The A/A genotype and the A allele of the g.3296G>A polymorphism were associated with KC occurrence, while the G allele was negatively correlated with it. We observed a decrease in KC occurrence associated with the A/G genotype of the g.3481A>G polymorphism. We did not find any association between the c.–2G>A polymorphism and KC. No association was found between all three polymorphisms and FECD occurrence.

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A Tripartite, Hierarchical Sigma Factor Cascade Promotes Hormogonium Development in the Filamentous Cyanobacterium Nostoc punctiforme

mSphere ◽

10.1128/msphere.00231-19 ◽

2019 ◽

Vol 4 (3) ◽

Cited By ~ 8

Author(s):

Alfonso Gonzalez ◽

Kelsey W. Riley ◽

Thomas V. Harwood ◽

Esthefani G. Zuniga ◽

Douglas D. Risser

Keyword(s):

Sigma Factor ◽

Dominant Role ◽

Sigma Factors ◽

Oxygenic Photosynthesis ◽

Model Organisms ◽

Filamentous Cyanobacterium ◽

Nostoc Punctiforme ◽

Filamentous Cyanobacteria ◽

Content Type ◽

Nitrogen Cycles

ABSTRACT Cyanobacteria are prokaryotes capable of oxygenic photosynthesis, and frequently, nitrogen fixation as well. As a result, they contribute substantially to global primary production and nitrogen cycles. Furthermore, the multicellular filamentous cyanobacteria in taxonomic subsections IV and V are developmentally complex, exhibiting an array of differentiated cell types and filaments, including motile hormogonia, making them valuable model organisms for studying development. To investigate the role of sigma factors in the gene regulatory network (GRN) controlling hormogonium development, a combination of genetic, immunological, and time-resolved transcriptomic analyses were conducted in the model filamentous cyanobacterium Nostoc punctiforme, which, unlike other common model cyanobacteria, retains the developmental complexity of field isolates. The results support a model where the hormogonium GRN is driven by a hierarchal sigma factor cascade, with sigJ activating the expression of both sigC and sigF, as well as a substantial portion of additional hormogonium-specific genes, including those driving changes to cellular architecture. In turn, sigC regulates smaller subsets of genes for several processes, plays a dominant role in promoting reductive cell division, and may also both positively and negatively regulate sigJ to reinforce the developmental program and coordinate the timing of gene expression, respectively. In contrast, the sigF regulon is extremely limited. Among genes with characterized roles in hormogonium development, only pilA shows stringent sigF dependence. For sigJ-dependent genes, a putative consensus promoter was also identified, consisting primarily of a highly conserved extended −10 region, here designated a J-Box, which is widely distributed among diverse members of the cyanobacterial lineage. IMPORTANCE Cyanobacteria are integral to global carbon and nitrogen cycles, and their metabolic capacity coupled with their ease of genetic manipulation make them attractive platforms for applications such as biomaterial and biofertilizer production. Achieving these goals will likely require a detailed understanding and precise rewiring of these organisms’ GRNs. The complex phenotypic plasticity of filamentous cyanobacteria has also made them valuable models of prokaryotic development. However, current research has been limited by focusing primarily on a handful of model strains which fail to reflect the phenotypes of field counterparts, potentially limiting biotechnological advances and a more comprehensive understanding of developmental complexity. Here, using Nostoc punctiforme, a model filamentous cyanobacterium that retains the developmental range of wild isolates, we define previously unknown definitive roles for a trio of sigma factors during hormogonium development. These findings substantially advance our understanding of cyanobacterial development and gene regulation and could be leveraged for future applications.

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