A Brief History of Ferritin, an Ancient and Versatile Protein.

Ferritin, a highly conserved iron storage protein, is among the earliest proteins that have been purified, named, and characterized due to its unique properties that continue to captivate researchers. Ferritin is composed of 24 subunits that form an almost spherical shell delimiting a cavity where thousands of iron atoms can be stored in a nontoxic ferric form, thereby preventing cytosolic iron from catalyzing oxidative stress. Mitochondrial and extracellular ferritin have also been described and characterized, with the latter being associated with several signaling functions.

A simple and highly sensitive colorimetric assay for the visual detection of lead and chromium using ascorbic acid capped gold nanoparticles.

Lead (Pb) and hexavalent chromium (Cr) are highly toxic pollutants with no safe exposure levels, posing significant health risks globally, especially in developing countries. Current detection methods for these metals are often complex and inaccessible, highlighting the urgent need for innovative approaches. In this study, we present a rapid, cost-effective colorimetric assay utilizing ascorbic acid-capped gold nanoparticles (AuNPs) for the selective detection of Pb and Cr ions at levels recommended by regulatory bodies such as the WHO and EPA.

Effects of ferritin iron loading, subunit composition, and the NCOA4-iron sulfur cluster on ferritin-NCOA4 interactions: An isothermal titration calorimetry study.

Ferritin is a 24-mer protein nanocage that stores iron and regulates intracellular iron homeostasis. The nuclear receptor coactivator-4 (NCOA4) binds specifically to ferritin H subunits and facilitates the autophagic trafficking of ferritin to the lysosome for degradation and iron release. Using isothermal titration calorimetry (ITC), we studied the thermodynamics of the interactions between ferritin and the soluble fragment of NCOA4 (residues 383-522), focusing on the effects of the recently identified FeS cluster bound to NCOA4, ferritin subunit composition, and ferritin-iron loading.

Unveiling the stochastic nature of human heteropolymer ferritin self-assembly mechanism.

Despite ferritin's critical role in regulating cellular and systemic iron levels, our understanding of the structure and assembly mechanism of isoferritins, discovered over eight decades ago, remains limited. Unveiling how the composition and molecular architecture of hetero-oligomeric ferritins confer distinct functionality to isoferritins is essential to understanding how the structural intricacies of H and L subunits influence their interactions with cellular machinery. In this study, ferritin heteropolymers with specific H to L subunit ratios were synthesized using a uniquely engineered plasmid design, followed by high-resolution cryo-electron microscopy analysis and deep learning-based amino acid modeling.

Detection of proteins with ascorbic acid-capped gold nanoparticles: a simple and highly sensitive colorimetric assay.

We report a simple and highly sensitive colorimetric method for the detection and quantification of proteins, based on the aggregation of ascorbic acid (AA) capped gold nanoparticles (AuNPs) by proteins. The interactions between our AuNPs and nine different proteins of various sizes and shapes (cytochrome C (12 kDa), lysozyme (14.3 kDa), myoglobin (17 kDa), human serum albumin (66 kDa), bovine serum albumin (66.

Structural basis for the intracellular regulation of ferritin degradation.

The interaction between nuclear receptor coactivator 4 (NCOA4) and the iron storage protein ferritin is a crucial component of cellular iron homeostasis. The binding of NCOA4 to the FTH1 subunits of ferritin initiates ferritinophagy-a ferritin-specific autophagic pathway leading to the release of the iron stored inside ferritin. The dysregulation of NCOA4 is associated with several diseases, including neurodegenerative disorders and cancer, highlighting the NCOA4-ferritin interface as a prime target for drug development.

Ferritin microheterogeneity, subunit composition, functional, and physiological implications.

Ferritin is a ubiquitous intracellular iron storage protein that plays a crucial role in iron homeostasis. Animal tissue ferritins consist of multiple isoforms (or isoferritins) with different proportions of H and L subunits that contribute to their structural and compositional heterogeneity, and thus physiological functions. Using size exclusion and anion exchange chromatography, capillary isoelectric focusing (cIEF), and SDS-capillary gel electrophoresis (SDS-CGE), we reveal for the first time a significant variation in ferritin subunit composition and isoelectric points, in both recombinant and native ferritins extracted from animal organs.

Micromagnetic and morphological characterization of heteropolymer human ferritin cores.

The physical properties of iron-reconstituted and genetically engineered human heteropolymer ferritins were investigated. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), electron energy-loss spectroscopy (EELS), and Fe Mössbauer spectroscopy were employed to ascertain (1) the microstructural, electronic, and micromagnetic properties of the nanosized iron cores, and (2) the effect of the H and L ferritin subunit ratios on these properties. Mössbauer spectroscopic signatures indicate that all iron within the core is in the high spin ferric state.

Hyperthermostable recombinant human heteropolymer ferritin derived from a novel plasmid design.

Mammalian ferritins are predominantly heteropolymeric species consisting of 2 structurally similar, but functionally and genetically distinct subunit types, called H (Heavy) and L (Light). The two subunits co-assemble in different H and L ratios to form 24-mer shell-like protein nanocages where thousands of iron atoms can be mineralized inside a hollow cavity. Here, we use differential scanning calorimetry (DSC) to study ferritin stability and understand how various combinations of H and L subunits confer aspects of protein structure-function relationships.

Ferritin nanocages as efficient nanocarriers and promising platforms for COVID-19 and other vaccines development.

Background: The development of safe and effective vaccines against SARS-CoV-2 and other viruses with high antigenic drift is of crucial importance to public health. Ferritin is a well characterized and ubiquitous iron storage protein that has emerged not only as a useful nanoreactor and nanocarrier, but more recently as an efficient platform for vaccine development.

Scope Of Review: This review discusses ferritin structure-function properties, self-assembly, and novel bioengineering strategies such as interior cavity and exterior surface modifications for cargo encapsulation and delivery.

Effect of Phosphate and Ferritin Subunit Composition on the Kinetics, Structure, and Reactivity of the Iron Core in Human Homo- and Heteropolymer Ferritins.

Ferritins are highly conserved supramolecular protein nanostructures that play a key role in iron homeostasis. Thousands of iron atoms can be stored inside their hollow cavity as a hydrated ferric oxyhydroxide mineral. Although phosphate associates with the ferritin iron nanoparticles, the effect of physiological concentrations on the kinetics, structure, and reactivity of ferritin iron cores has not yet been explored.

Iron Mobilization from Ferritin in Yeast Cell Lysate and Physiological Implications.

Most in vitro iron mobilization studies from ferritin have been performed in aqueous buffered solutions using a variety of reducing substances. The kinetics of iron mobilization from ferritin in a medium that resembles the complex milieu of cells could dramatically differ from those in aqueous solutions, and to our knowledge, no such studies have been performed. Here, we have studied the kinetics of iron release from ferritin in fresh yeast cell lysates and examined the effect of cellular metabolites on this process.

A Novel Approach for the Synthesis of Human Heteropolymer Ferritins of Different H to L Subunit Ratios.

Mammalian ferritins are predominantly heteropolymeric species consisting of 24 structurally similar, but functionally different subunit types, named H and L, that co-assemble in different proportions. Despite their discovery more than 8 decades ago, recombinant human heteropolymer ferritins have never been synthesized, owing to the lack of a good expression system. Here, we describe for the first time a unique approach that uses a novel plasmid design that enables the synthesis of these complex ferritin nanostructures.

Calibration of mammalian skeletal muscle Ca transients recorded with the fast Ca dye Mag-Fluo-4.

Background: Mag-Fluo-4 is increasingly employed for studying Ca signaling in skeletal muscle; however, the lack of information on the Ca-Mag-Fluo-4 reaction limits its wider usage.

Methods: Fluorescence and isothermal titration calorimetry (ITC) experiments were performed to determine the binding stoichiometry (n) and thermodynamics (enthalpy (ΔH) and entropy (ΔS) changes), as well as the in vitro and in situ K of the Ca-Mag-Fluo-4 reaction. Rate constants (k, k), fluorescence maximum (F), minimum (F), and the dye compartmentalization were also estimated.

Complexation of ferrous ions by ferrozine, 2,2'-bipyridine and 1,10-phenanthroline: Implication for the quantification of iron in biological systems.

Iron is an essential nutrient for virtually all forms of life. Because of its redox properties and involvement in a wide range of biological processes, a number of qualitative and quantitative chemical tools have been developed to detect reduced (Fe) and oxidized (Fe) forms of iron in biomolecules. These types of measurements are not only important in detecting iron species in solution, but also in understanding iron distribution, accumulation, and role in physiological and pathological processes.

Fenretinide binding to the lysosomal protein saposin D alters ceramide solubilization and hydrolysis.

Fenretinide is a synthetic retinoid pharmaceutical linked to ceramide build-up . Saposin D is an intralysosomal protein necessary for ceramide binding/degradation. We show, electronic absorption spectroscopy, fluorescence spectroscopy, and ceramide hydrolysis assays, that fenretinide is bound by saposin D { = (1.

Iron mineralization and core dissociation in mammalian homopolymeric H-ferritin: Current understanding and future perspectives.

Background: The mechanism of iron oxidation and core formation in homopolymeric H-type ferritins has been extensively studied in-vitro, so has the reductive mobilization of iron from the inorganic iron(III) core. However, neither process is well-understood in-vivo despite recent scientific advances.

Scope Of Review: Here, we provide a summary of our current understanding of iron mineralization and iron core dissolution in homopolymeric H-type ferritins and highlight areas of interest and further studies that could answer some of the outstanding questions of iron metabolism.

Thermodynamic and Kinetic Studies of the Interaction of Nuclear Receptor Coactivator-4 (NCOA4) with Human Ferritin.

Ferritinophagy is a ferritin autophagic degradation process mediated by the selective nuclear receptor coactivator-4 (NCOA4). NCOA4 binds to ferritin and delivers it to nascent autophagosomes, which then merge with the lysosomes for ferritin degradation and iron release. Earlier studies have demonstrated a specific association of NCOA4 with ferritin H-subunits, but not L-subunits.

Mutant L-chain ferritins that cause neuroferritinopathy alter ferritin functionality and iron permeability.

In mammals, the iron storage and detoxification protein ferritin is composed of two functionally and genetically distinct subunit types, H (heavy) and L (light). The two subunits co-assemble in various ratios, with a tissue specific distribution, to form shell-like protein structures of 24 subunits within which a mineralized iron core is stored. The H-subunits possess ferroxidase centers that catalyze the rapid oxidation of ferrous ions, whereas the L-subunit does not have such centers and is believed to play an important role in electron transfer reactions that occur during the uptake and release of iron.

Ferritin exhibits Michaelis-Menten behavior with oxygen but not with iron during iron oxidation and core mineralization.

The excessively high and inconsistent literature values for Km,Fe and Km,O2 prompted us to examine the iron oxidation kinetics in ferritin, the major iron storage protein in mammals, and to determine whether a traditional Michaelis-Menten enzymatic behavior is obeyed. The kinetics of Fe(ii) oxidation and mineralization catalyzed by three different types of ferritins (recombinant human homopolymer 24H, HuHF, human heteropolymer ∼21H:3L, HL, and horse spleen heteropolymer ∼3.3H:20.

Reductive Mobilization of Iron from Intact Ferritin: Mechanisms and Physiological Implication.

Ferritins are highly conserved supramolecular protein nanostructures composed of two different subunit types, H (heavy) and L (light). The two subunits co-assemble into a 24-subunit heteropolymer, with tissue specific distributions, to form shell-like protein structures within which thousands of iron atoms are stored as a soluble inorganic ferric iron core. In-vitro (or in cell free systems), the mechanisms of iron(II) oxidation and formation of the mineral core have been extensively investigated, although it is still unclear how iron is loaded into the protein in-vivo.

[The myth of virgin cleansing: Latest news on an archaic magico-religious practice].

Background: In the medical anthropology section of the Nanterre Hospital (France) for migrants and refugees, three cases were recorded of "virgin cleansing" in sub-Saharan African countries.

Patients And Methods: These consisted of sexual assaults (2 instances of rape and 1 of sexual interference) on sexually immature females (young girls) by patients with sexually transmitted infections (mainly HIV, syphilis) hoping they might thereby be cured.

Discussion: These particularly atrocious hetero-aggressive sexual practices based on magical arguments are unfortunately universal and are not limited to a specific culture.

Exploring the Multiligand Binding Specificity of Saposin B Reveals Two Binding Sites.

Saposin B (SapB) is a human lysosomal protein, critical for the degradation of -sulfogalactosylceramide (sulfatide). SapB binds sulfatide and presents it to the active site of the enzyme arylsulfatase A. Deficiency of SapB leads to fatal activator-deficient metachromatic leukodystrophy.