Metallomics最新文献

Iron-sulfur (Fe-S) clusters are ancient and versatile cofactors that drive essential cellular functions, from electron transport to enzyme catalysis. Their intrinsic sensitivity to oxidation has shaped the evolution of specialized Fe-S cluster biosynthetic and protective mechanisms. Recent findings highlight how human Fe-S-binding regulators exploit this cofactor's reactivity to sense iron and oxygen levels, translating environmental cues into appropriate homeostatic responses. Yet, the same redox sensitivity also renders Fe-S cluster proteins and biosynthesis particularly vulnerable to high oxygen tensions, contributing to pathological outcomes. In this minireview, we examine key discoveries illustrating how Fe-S clusters and oxygen intersect to influence both human health and disease. Finally, we discuss how identifying novel Fe-S targets and regulatory circuits may open innovative therapeutic avenues-harnessing oxygen itself as a strategic element in managing relevant disorders.

Pseudomonas aeruginosa is a major contributor to human infections and is widely distributed in the environment. Its ability for growth under aerobic and anaerobic conditions provides adaptability to environmental changes and in confronting immune responses. We applied native 2-dimensional metalloproteomics to P. aeruginosa to examine how use of iron within the metallome responds to oxic and anoxic conditions. Analyses revealed four iron peaks comprised of metalloproteins with synergistic functions, including (1) respiratory and metabolic enzymes, (2) oxidative stress response enzymes, (3) DNA synthesis and nitrogen assimilation enzymes, and (4) denitrification enzymes and related copper enzymes. Fe Peaks were larger under anoxic conditions, consistent with increased iron demand due to anaerobic metabolism and with the denitrification peak absent under oxic conditions. Three ferritins co-eluted with the first and third iron peaks, localizing iron storage with these functions. Several enzymes were more abundant at low oxygen, including alkylhydroperoxide reductase C that deactivates organic radicals produced by denitrification, all three classes of ribonucleotide reductases (including monomer and oligomer forms), ferritin (increasing in ratio relative to bacterioferritin), and denitrification enzymes. Superoxide dismutase and homogentisate 1,2-dioxygenase were more abundant at high oxygen. Several Fe Peaks contained iron metalloproteins that co-eluted earlier than their predicted size, implying additional protein-protein interactions and suggestive of cellular organization that contributes to iron prioritization in Pseudomonas with its large genome and flexible metabolism. This study characterized the iron metalloproteome of one of the more complex prokaryotic microorganisms, attributing enhanced iron use under anaerobic denitrifying metabolism to its specific metalloprotein constituents.

Iron dyshomeostasis in neurons, involving iron accumulation and abnormal redox balance, is implicated in neurodegeneration. In particular, labile iron, a highly reactive pool of intracellular iron, plays a prominent role in iron-induced neurological damage. However, the mechanisms governing the detoxification and transport of labile iron within neurons are not fully understood. This study investigates the storage and transport of labile ferrous iron Fe(II) in cultured primary rat hippocampal neurons. Iron distribution was studied using live cell fluorescence microscopy with a selective labile Fe(II) fluorescent dye, and synchrotron X-ray fluorescence microscopy (SXRF) for total iron distribution. Fluorescent labeling of the axon initial segment and of lysosomes allowed iron distribution to be correlated with these subcellular compartments. The results show that labile Fe(II) is stored in lysosomes within somas, axons, and dendrites and that lysosomal labile Fe(II) is transported retrogradely and anterogradely along axons and dendrites. In addition, SXRF imaging of total iron confirms iron uptake and iron distribution in the form of iron-rich dots in the soma and neurites. These results suggest that after exposure to Fe(II), labile Fe(II) is stored in lysosomes and can be transported along dendrites and axons. These storage and transport mechanisms could be associated with the detoxification of reactive Fe(II) in lysosomes, which protects cellular structures from oxidative stress. They could also be associated with the metabolic functions of iron in the soma, axons, and dendrites. In this case, easily exchangeable Fe(II) is transported in lysosomes to the neuronal compartments where iron is required.

Six Hyp (A through F) proteins synthesize the NiFe(CN)2CO cofactor found in all [NiFe]-hydrogenases. The Fe(CN)2CO moiety of this cofactor is assembled on a separate scaffold complex comprising HypC and HypD. HypE and HypF generate the cyanide ligands from carbamoyl phosphate by converting the carbamoyl moiety to a thiocyanate associated with HypE's C-terminal cysteine residue, within a conserved 'PRIC' motif. Here, we identify amino acid residue D98 in the central cleft of HypD to be required for biosynthesis of the Fe(CN)2CO moiety and for optimal interaction of HypD with HypE. Construction of a D98A amino acid variant of HypD caused near-complete loss of hydrogenase activity in anaerobically grown Escherichia coli cells, while exchange of the structurally proximal, but non-conserved, residue S356 on HypD, did not. Native mass spectrometric analysis of the anaerobically purified HypC-HypDD98A scaffold complex revealed only a low amount of the bound Fe(CN)2CO group. Western blotting experiments revealed that purified scaffold complexes between either HypC or HybG (a paralogue of HypC) with HypD-D98A showed a strongly impaired interaction with HypE. Examination of the HypCDE complex crystal structure from Thermococcus kodakarensis revealed that D98 of HypD lies within a cleft through which the C-terminus of HypE can access the bound iron ion on HypCD. Alphafold3 predictions suggest that the D98 residue interacts with the arginine residue of the 'PRIC' motif at the C-terminus of HypE to position the modified terminal cysteine residue precisely for delivery of cyanide to the iron ion associated with the HypCD complex.

The large subunit of all [NiFe]-hydrogenases in bacteria and archaea has a heterobimetallic NiFe(CN)2CO cofactor coordinated by four cysteine residues. The iron ion has two cyanides and a carbon monoxide as diatomic ligands. Six ancillary Hyp (ABCDEF) proteins are necessary for anaerobic synthesis of this cofactor, while under oxic conditions at least one further protein, HypX, is required for CO synthesis. The Fe(CN)2CO moiety of the cofactor is synthesized on a separate HypCD scaffold complex. Nickel is inserted into the apo-large subunit only after Fe(CN)2CO has been introduced. Recent biochemical and structural studies have significantly advanced our understanding of cofactor biosynthesis for these important metalloenzymes. Despite these gains in mechanistic insight, many questions still remain, the most pressing of which is the origin of the CO ligand in anaerobic microorganisms. This minireview provides an overview of the current status of this research field and highlights recent advances and unresolved issues.

Zinc (Zn²⁺) plays a pivotal role in T-cell activation by modulating the interactions between the co-receptors CD4 and CD8α and the Src-family kinase Lck. A central structural feature in this regulation is the zinc clasp, a Zn²⁺-mediated CD4/CD8α-Lck receptor interface that stabilizes these complexes during T cell receptor signaling. Recent findings reveal that the stability of CD4-Lck and CD8α-Lck complexes is differentially regulated by Zn²⁺, which acts as a dynamic signaling molecule during T-cell activation. Here, we discuss the structural dynamics of these interactions and the impact of Zn²⁺ on CD4 dimerization, palmitoylation, and membrane interactions, which are crucial for effective T-cell responses. These mechanisms underscore a broader framework in which zinc biology intersects with co-receptor-Lck coupling to guide T-cell development, lineage fidelity, and functional specialization. Beyond immunobiology, zinc-dependent protein-protein interactions offer promising opportunities for biotechnological innovation, particularly in the design of molecular systems that exploit zinc-mediated structural control.

Selenoneine (SEN), a selenium analog of ergothioneine (EGT), is widely distributed in marine fish and is a strong radical scavenger. Electron spin resonance spectrometry showed that SEN monomer and dimer directly scavenged ·OH generated by irradiating hydrogen peroxide (H2O2) with ultraviolet light. The radical scavenging capacity was stronger for SEN monomer, dimer, and EGT in that order. Mass spectrometry analyses revealed that the monomer and dimer were oxidized to SEN seleninic acid (SEN-seleninic acid) in the presence of H2O2, and that SEN-seleninic acid was reduced to SEN monomer by reduced glutathione (GSH). These reactions proceeded at physiological concentrations of H2O2 and GSH. Our findings suggest that SEN scavenges ·OH directly by a rapid, repetitive nonenzymatic reaction via self-oxidation and by its reduction back to SEN.

Administration of the cadmium-metallothionein (Cd-MT) complex has been known to cause acute nephrotoxicity due to free Cd ions during the breakdown of the Cd-MT protein in renal cells. However, the fate of the renal Cd after Cd-MT administration remains elusive. We applied Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to visualize Cd distribution in the kidneys of mice administered Cd-MT. In the initial several hours, Cd was detected predominantly in the renal cortex. Elevated urinary β2-microglobulin and glucose within a day and rapid induction of MT-I mRNA indicated the generation of toxic free Cd ions. Unexpectedly, however, the Cd distribution changed drastically: from the cortex to the boundary of the cortex and outer medulla until 3 days. From 3 to 18 h, renal Cd concentrations decreased rapidly, accompanied by a large amount of urinary Cd excretion. These results suggest that the injected Cd-MT was transiently distributed in the surface nephrons in the cortex, and the free Cd ions derived from the decomposed Cd-MT were released into the lumen of proximal tubules and then partly reabsorbed at the boundary of the cortex and outer medulla, where the S3-segment proximal tubules exist abundantly. Thus, the LA-ICP-MS revealed dynamic changes in Cd distribution, suggesting the intra-renal transport of the Cd-MT-derived free Cd ions in the kidneys.

Volcanic ash is a significant source of micronutrients including iron (Fe), copper (Cu), and zinc (Zn) in oligotrophic tropical waters. These bioactive metals enhance primary productivity, influencing local and global biogeochemical cycles. This study explores how volcanic ash exposure affects trace metal uptake and photophysiological response, and how redox-sensitive metal stable isotope measurements in the tissues of the scleractinian coral Stylophora pistillata can provide crucial information on coral health. Controlled coral culture experiments were conducted in which coral nubbins were exposed to varying intensity and duration of volcanic ash. Throughout the experiment, coral symbionts showed enhanced photosynthetic performance irrespective of intensity or duration of ash exposure. Stable isotopes, such as δ65Cu and δ56Fe, in the coral tissue are marked by systematic variations, not associated with intensity or duration of ash exposure. Instead, we suggest biologically modulated redox-sensitive fractionation associated with ash exposure, linked to the coral host's oxidative stress state. This is evidenced by significant correlations between δ65Cu in coral hosts and photophysiology, with lighter Cu isotope ratios associated with higher photosynthetic performances. Hence, we propose that δ65Cu, and more generally redox-sensitive isotopic ratios (i.e. δ56Fe), in coral hosts serves as an indicator of the physiological state of symbiotic corals.

In an attempt to treat neglected diseases such as leishmaniasis and fungal infections, three novel copper(II) hybrid have been developed: [Cu(dppz)(CTZ)(NO3)](NO3) (1), [Cu(dppz)(KTZ)(H2O)(NO3)](NO3) (2), and [Cu(dppz)(FLZ)(NO3)]2(NO3)2 (3). They were synthesized by coordinating antifungal imidazole based drugs and dipyridophenazine as ligands to copper(II) under mild conditions and in good yields. These coordination compounds were characterized by various analytical and spectroscopic techniques which confirmed the coordination of both ligands to the metal, and the monodentate (1) or bidentate (2 and 3) coordination of the nitrate and as counterion. These copper hybrids were stable in solid state, in dimethyl sulfoxide (DMSO) and the DMSO-water mixture. DNA interactions were studied using absorption and fluorescence titrations, viscosity measurements, and electrophoresis assays. Complexes 1 and 2 formed strong interaction with DNA. The activity against Leishmania was the highest with complex 3, unlike against Sporothrix brasiliensis, where the free imidazole-based drugs (ITZ and KTZ) performed better.