The importance of eukaryotic ferritins in iron handling and cytoprotection

2015 ◽  
Vol 472 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Paolo Arosio ◽  
Fernando Carmona ◽  
Raffaella Gozzelino ◽  
Federica Maccarinelli ◽  
Maura Poli
Keyword(s):  
Immune Response ◽  
Innate Immunity ◽  
Animal Models ◽  
Storage Proteins ◽  
Eukaryotic Cells ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Iron Incorporation ◽  
Iron Storage Proteins ◽  
Response Activation

Ferritins, the main intracellular iron storage proteins, have been studied for over 60 years, mainly focusing on the mammalian ones. This allowed the elucidation of the structure of these proteins and the mechanisms regulating their iron incorporation and mineralization. However, ferritin is present in most, although not all, eukaryotic cells, comprising monocellular and multicellular invertebrates and vertebrates. The aim of this review is to provide an update on the general properties of ferritins that are common to various eukaryotic phyla (except plants), and to give an overview on the structure, function and regulation of ferritins. An update on the animal models that were used to characterize H, L and mitochondrial ferritins is also provided. The data show that ferritin structure is highly conserved among different phyla. It exerts an important cytoprotective function against oxidative damage and plays a role in innate immunity, where it also contributes to prevent parenchymal tissue from the cytotoxicity of pro-inflammatory agonists released by the activation of the immune response activation. Less clear are the properties of the secretory ferritins expressed by insects and molluscs, which may be important for understanding the role played by serum ferritin in mammals.

scholarly journals A Ferritin Mutant of Mycobacterium tuberculosis Is Highly Susceptible to Killing by Antibiotics and Is Unable To Establish a Chronic Infection in Mice

2012 ◽  
Vol 80 (10) ◽  
pp. 3650-3659 ◽  
Author(s):  
Ruchi Pandey ◽  
G. Marcela Rodriguez
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Iron Homeostasis ◽  
Storage Proteins ◽  
Iron Acquisition ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Content Type ◽  
Iron Storage Proteins

ABSTRACTIron is an essential, elusive, and potentially toxic nutrient for most pathogens, includingMycobacterium tuberculosis. Due to the poor solubility of ferric iron under aerobic conditions, free iron is not found in the host.M. tuberculosisrequires specialized iron acquisition systems to replicate and cause disease. It also depends on a strict control of iron metabolism and intracellular iron levels to prevent iron-mediated toxicity. Under conditions of iron sufficiency,M. tuberculosisrepresses iron acquisition and induces iron storage, suggesting an important role for iron storage proteins in iron homeostasis.M. tuberculosissynthesizes two iron storage proteins, a ferritin (BfrB) and a bacterioferritin (BfrA). The individual contributions of these proteins to the adaptive response ofM. tuberculosisto changes in iron availability are not clear. By generating individual knockout strains ofbfrAandbfrB, the contribution of each one of these proteins to the maintenance of iron homeostasis was determined. The effect of altered iron homeostasis, resulting from impaired iron storage, on the resistance ofM. tuberculosistoin vitroandin vivostresses was examined. The results show that ferritin is required to maintain iron homeostasis, whereas bacterioferritin seems to be dispensable for this function.M. tuberculosislacking ferritin suffers from iron-mediated toxicity, is unable to persist in mice, and, most importantly, is highly susceptible to killing by antibiotics, showing that endogenous oxidative stress can enhance the antibiotic killing of this important pathogen. These results are relevant for the design of new therapeutic strategies againstM. tuberculosis.

scholarly journals Structure and function of a 9.6 megadalton bacterial iron storage compartment

2019 ◽  
Author(s):  
T. W. Giessen ◽  
B. J. Orlando ◽  
A. A. Verdegaal ◽  
M. G. Chambers ◽  
J. Gardener ◽  
...  
Keyword(s):  
Iron Homeostasis ◽  
Storage Proteins ◽  
Essential Element ◽  
Redox Balance ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Storage Compartment ◽  
X Ray Crystallography ◽  
Iron Storage Proteins ◽  
Assembly Principles

AbstractIron storage proteins are essential for maintaining intracellular iron homeostasis and redox balance. Iron is generally stored in a soluble and bioavailable form inside ferritin protein compartments. However, some organisms do not encode ferritins and thus rely on alternative storage strategies. Encapsulins, a class of protein-based organelles, have recently been implicated in microbial iron and redox metabolism. Here, we report the structural and mechanistic characterization of a 42 nm two-component encapsulin-based iron storage compartment from Quasibacillus thermotolerans. Using cryo-electron microscopy and x-ray crystallography, we reveal the assembly principles of a thermostable T = 4 shell topology and its catalytic ferroxidase cargo. We show that the cargo-loaded compartment has an exceptionally large iron storage capacity storing over 23,000 iron atoms. These results form the basis for understanding alternate microbial strategies for dealing with the essential element iron.

scholarly journals Evidence that the specificity of iron incorporation into homopolymers of human ferritin L- and H-chains is conferred by the nucleation and ferroxidase centres

1996 ◽  
Vol 314 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Paolo SANTAMBROGIO ◽  
Sonia LEVI ◽  
Anna COZZI ◽  
Barbara CORSI ◽  
Paolo AROSIO
Keyword(s):  
Storage Proteins ◽  
Iron Storage ◽  
Cellular Iron ◽  
Iron Incorporation ◽  
Ferroxidase Activity ◽  
Iron Storage Proteins ◽  
The Difference ◽  
Induced Aggregation

Mammalian ferritins are iron-storage proteins made of 24 subunits of two types: the H- and L-chains. L-chains, in contrast with H-chains, lack detectable ferroxidase activity. When ferritins were subjected to iron loading in vitro with increments near the saturation limit of 4000 Fe atoms per molecule, the homopolymers of human H-chains formed insoluble aggregates, caused by non-specific iron hydrolysis, whereas the homopolymers of L-chains remained soluble and incorporated most of the available iron. To analyse the molecular reasons for the difference, Glu-57 and Glu-60, which are conserved and exposed on the cavity of L-chains, were substituted with His, as in H-chains. The double substitution made the L-homopolymers as sensitive as the H-homopolymers to the iron-induced aggregation, whereas the opposite substitution in the H-chain increased homopolymer resistance to the aggregation only marginally. Millimolar concentrations of citrate and phosphate increased iron incorporation in H-homopolymers by reducing non-specific iron hydrolysis, but inhibited that in L-homopolymers by sequestering available iron. The data indicate that the specific iron incorporation into L-homopolymers is mainly due to the iron-nucleation capacity of Glu-57, Glu-60 and other carboxyl groups exposed on the cavity; in contrast, the specificity of iron incorporation into H-homopolymers is related to its ferroxidase activity, which determines rapid Fe(III) accumulation inside the cavity. The finding that ferroxidase centres are essential for the incorporation of iron in the presence of likely candidates of cellular iron transport, such as phosphate and citrate, confirms their importance in ferritin function in vivo.

scholarly journals Distinct Effects of Escherichia coli,Pseudomonas aeruginosa and Staphylococcus aureus Cell Wall Component-Induced Inflammation on the Iron Metabolism of THP-1 Cells

2021 ◽  
Vol 22 (3) ◽  
pp. 1497
Author(s):  
Edina Pandur ◽  
Kitti Tamási ◽  
Ramóna Pap ◽  
Gergely Jánosa ◽  
Katalin Sipos
Keyword(s):  
Cell Wall ◽  
Inflammatory Cytokines ◽  
Iron Metabolism ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Storage Proteins ◽  
Iron Storage ◽  
E Coli ◽  
Iron Storage Proteins ◽  
Pro Inflammatory Cytokines

Macrophages are essential immune cells of the innate immune system. They participate in the development and regulation of inflammation. Macrophages play a fundamental role in fighting against bacterial infections by phagocytosis of bacteria, and they also have a specific role in immunomodulation by secreting pro-inflammatory cytokines. In bacterial infection, macrophages decrease the serum iron concentration by removing iron from the blood, acting as one of the most important regulatory cells of iron homeostasis. We examined whether the Gram-positive and Gram-negative cell wall components from various bacterial strains affect the cytokine production and iron transport, storage and utilization of THP-1 monocytes in different ways. We found that S. aureus lipoteichoic acid (LTA) was less effective in activating pro-inflammatory cytokine expression that may related to its effect on fractalkine production. LTA-treated cells increased iron uptake through divalent metal transporter-1, but did not elevate the expression of cytosolic and mitochondrial iron storage proteins, suggesting that the cells maintained iron efflux via the ferroportin iron exporter. E. coli and P. aeruginosa lipopolysaccharides (LPSs) acted similarly on THP-1 cells, but the rates of the alterations of the examined proteins were different. E. coli LPS was more effective in increasing the pro-inflammatory cytokine production, meanwhile it caused less dramatic alterations in iron metabolism. P. aeruginosa LPS-treated cells produced a smaller amount of pro-inflammatory cytokines, but caused remarkable elevation of both cytosolic and mitochondrial iron storage proteins and intracellular iron content compared to E. coli LPS. These results prove that LPS molecules from different bacterial sources alter diverse molecular mechanisms in macrophages that prepossess the outcome of the bacterial infection.

scholarly journals PerR Controls Oxidative Stress Resistance and Iron Storage Proteins and Is Required for Virulence in Staphylococcus aureus

2001 ◽  
Vol 69 (6) ◽  
pp. 3744-3754 ◽  
Author(s):  
Malcolm J. Horsburgh ◽  
Mark O. Clements ◽  
Howard Crossley ◽  
Eileen Ingham ◽  
Simon J. Foster
Keyword(s):  
Oxidative Stress ◽  
Staphylococcus Aureus ◽  
Stress Resistance ◽  
Iron Homeostasis ◽  
Storage Proteins ◽  
Iron Storage ◽  
Oxidative Stress Resistance ◽  
Genes Encoding ◽  
Starvation Survival ◽  
Iron Storage Proteins

ABSTRACT The Staphylococcus aureus genome encodes three ferric uptake regulator (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of PerR, we inactivated the gene by allelic replacement using a kanamycin cassette, creating strain MJH001 (perR). PerR was found to control transcription of the genes encoding the oxidative stress resistance proteins catalase (KatA), alkyl hydroperoxide reductase (AhpCF), bacterioferritin comigratory protein (Bcp), and thioredoxin reductase (TrxB). Furthermore, PerR regulates transcription of the genes encoding the iron storage proteins ferritin (Ftn) and the ferritin-like Dps homologue, MrgA. Transcription of perR was autoregulated, and PerR repressed transcription of the iron homeostasis regulator Fur, which is a positive regulator of catalase expression. PerR functions as a manganese-dependent, transcriptional repressor of the identified regulon. Elevated iron concentrations produced induction of the PerR regulon. PerR may act as a peroxide sensor, since addition of external hydrogen peroxide to 8325-4 (wild type) resulted in increased transcription of most of the PerR regulon, except forfur and perR itself. The PerR-regulatedkatA gene encodes the sole catalase of S. aureus, which is an important starvation survival determinant but is surprisingly not required for pathogenicity in a murine skin abscess model of infection. In contrast, PerR is not necessary for starvation survival but is required for full virulence (P < 0.005) in this model of infection. PerR ofS. aureus may act as a redox sentinel protein during infection, analogous to the in vitro activities of OxyR and PerR ofEscherichia coli and Bacillus subtilis, respectively. However, it differs in its response to the metal balance within the cell and has the added capability of regulating iron uptake and storage.

On the magnetic ordering of the iron storage proteins in tissues

2004 ◽  
Vol 272-276 ◽  
pp. 2422-2423 ◽  
Author(s):  
Olga Mykhaylyk ◽  
Gyula Török ◽  
Olexandr Dudchenko ◽  
Oksana Stavinska ◽  
Nataly Dudchenko ◽  
...  
Keyword(s):  
Storage Proteins ◽  
Magnetic Ordering ◽  
Iron Storage ◽  
Iron Storage Proteins
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