Metallomics最新文献

The molecular mechanism of aluminum toxicity in biological systems remains poorly understood. In this study, the relationship between aluminum and intracellular calcium was investigated in Saccharomyces cerevisiae model cells. Genetic analysis demonstrated that deletion mutants of plasma membrane calcium transport cch1Δ and mid1Δ, as well as the Golgi calcium pump deletion mutant pmr1Δ, increased the sensitivity to aluminum, while their sensibility could be compensated by exogenous calcium. Strains of cch1Δ and mid1Δ treated by Ca2+ chelator EGTA was more sensitive to aluminum compared with BY4741 and pmc1Δ. Further ICP-AES analysis showed that calcium uptake through both CCH1 and MID1 did not detoxify by inhibiting aluminum absorption. Meanwhile, aluminum treatment did not change the intracellular calcium uptake in cch1Δ, and mid1Δ, although it increased the mRNA levels of CCH1 or MID1 in all tested strains. It suggests that the increase in intracellular calcium induced by aluminum is CCH1 and MID1-dependent. Subsequently, the intracellular calcineurin-CRZ1 pathway was activated under aluminum stress to promote the expression of CCH1, MID1 and PMR1. Notably, overexpression of PMR1 significantly reduced intracellular aluminum levels and enhanced aluminum tolerance in both wild-type and mutant strains (cch1Δ, cnb1Δ, and crz1Δ). Furthermore, another vesicle transport deletion mutant gos1Δ or the strains (WT and gos1Δ) treated by BFA (a vesicle transport inhibitor) showed enhanced sensitivity to aluminum stress. However, exogenous calcium and/or PMR1 overexpression could reverse this sensitivity. Altogether, increasing intracellular calcium serves as a protective response to aluminum stress. The calcium-related signaling, particularly PMR1-mediated vesicle transport, plays a crucial role in aluminum detoxification.

Iron is an essential metal for almost all living organisms. The major 'consumers' of intracellular iron content are a group of proteins that require an iron-sulfur cluster for their functions. It has been shown that iron-sulfur clusters in proteins are assembled by a set of highly conserved proteins using intracellular free iron and L-cysteine as iron and sulfide sources, respectively. Ironically, excess iron is detrimental to cells as free ferrous iron promotes the production of reactive oxygen species via the Fenton reaction. In Escherichia coli, intracellular iron homeostasis is regulated primarily by a global transcription factor Fur (ferric uptake regulator). Since its discovery, it had been assumed that Fur binds ferrous iron to regulate intracellular iron homeostasis, oxidative stress response, and bacterial virulence, among others. However, the proposed 'iron-bound' Fur had never been identified in E. coli or any other bacteria. Recent studies have revealed that E. coli Fur binds a unique [2Fe-2S] cluster in response to elevation of intracellular free iron content, and that the [2Fe-2S] cluster in Fur is enzymatically assembled by the iron-sulfur cluster biogenesis machinery. Because Fur also regulates the expression of the genes encoding the iron-sulfur cluster assembly machinery, Fur represents a key link between biogenesis of iron-sulfur clusters and regulation of intracellular iron homeostasis in bacteria.

Iron is an essential micronutrient and plays a vital role in human nutrition and plant development. In this report, we investigated iron-binding proteins (IBPs) of bread wheat at the sequence and structure levels, utilizing high-throughput systematic computational biology and bioinformatic approaches. We found that out of 133 346 wheat proteins, at least 0.97% could bind with iron ions. The analysis revealed numerous significant differences among these IBPs, which are involved in various biological functions. Most of these proteins are localized in plastids, followed by the endoplasmic reticulum, cell membrane and nucleus. But the most diverse group of IBPs are localized in the nucleus and cytoplasm region, being functionally associated with various biological processes. Out of 321 IBP unique domains, most proteins fall under GT1-Gtf-like, protein kinase domain, secretory peroxidases and CYP1. Further categorization and classification of these shortlisted IBPs revealed that most of these proteins are involved in metabolic processes, with oxidoreductase activity being the most prominent gene ontology molecular function (GO: MF), whereas biological process (GO: BP) enrichment highlighted the involvement of these IBPs in the management of reactive oxygen species. Protein interaction and identification of hub genes revealed further important IBP genes that have the potential to be used as a reference sheet for wet-lab work in the development of molecular markers for biofortification and understanding iron homeostasis in wheat.

Novel monoribbed-functionalized iron(II) cage complexes with optically active and/or terminal biorelevant group(s) were designed and prepared by two-step nucleophilic substitution of their mono- and dichloroclathrochelate precursors. The single-crystal XRD structures of all of them and those of known leader iron(II)-centered cage bioeffector and of its reactive monochloroclathrochelate precursor were solved. These experimental data were used for theoretical quantum chemical calculations of electrostatic potentials for their 3D-shaped molecules. This allowed to localize the peripheral (exterior) biorelevant group(s), which are responsible for supramolecular binding of thus designed clathrochelate guests to globular proteins as the hosts. Host-guest binding in aqueous solutions between the unfolded protein macromolecules and all the aforementioned iron(II) complexes was studied by the circular dichroism method. An inherent chirality of the metalloclathrochelates with optically active ribbed substituent and a metal-centered chirality of all the prepared macrobicyclic compounds, induced by their supramolecular clathrochelate-to-protein binding, were observed.

Iron (Fe) and copper (Cu) are crucial micronutrients for plant growth and development. The yellow stripe-like (YSL) proteins play a vital role in the absorption and transport of metal chelates in plants. The YSL genes in tobacco have not been systematically identified and characterized. This study aims to explore the YSL genes in Nicotiana tabacum. A comprehensive set of 17 NtYSL genes were identified and classified into four distinct clades on the phylogenetic tree. The gene structures, characterized by the length and distribution of exons and introns, and protein motifs are relatively conserved. Genomic localization analysis revealed that the NtYSL genes are unevenly distributed across 15 chromosomes, with 11 pairs of homeologous loci identified within the genome. To investigate the functionality of these genes, we analyzed their expression levels in shoots and roots under Fe- and Cu-deficient conditions by real-time quantitative reverse transcription PCR (qRT-PCR), finding that several NtYSL genes are responsive to Cu deficiency or Fe deficiency. This study provides a systematic characterization of the NtYSL gene family in Nicotiana tabacum and offers insights into their potential roles in Fe and Cu homeostasis.

The complex interplay between metal abundance, transport mechanisms, cell distribution, and tumor progression-related biological pathways (e.g. metabolism, collagen remodeling) remains poorly understood. Traditionally, genes and metals have been studied in isolation, limiting insights into their interactions. Recent advances in spatial transcriptomics and elemental profiling now enable comprehensive exploration of tissue-wide metal-gene interactions, though integration remains challenging. In this proof-of-concept study, we investigated metal-dependent signaling within the tumor microenvironment of a unique colorectal cancer (CRC) tumor. We implemented a spatial multimodal workflow which integrated elemental imaging, gene expression, cellular composition, and histopathological features to uncover metals-related pathways through spatially resolved gene expression correlation analyses. Preliminary findings revealed significant associations, for instance: elevated iron correlated with mesenchymal phenotypes located at the tumor's proliferative front, correlating with expression of genes involved in the epithelial-to-mesenchymal transition pathways, and extracellular matrix remodeling. Preliminary observations from this single sample revealed that high copper concentrations were localized to regions of active tumor growth and were associated with increased expression of immune response genes. This proof-of-concept workflow demonstrates the feasibility of integrating elemental imaging with spatial transcriptomics to identify metals-based gene correlates. Future application of this workflow to larger patient cohorts will pave the way for expansive comparisons across the metallome and transcriptome, ultimately identifying novel targets for tumor progression biomarkers and therapeutic interventions.

Manganese (Mn) plays a dual role in the body, acting as an essential trace element and a potential toxicant, the effects of which depend on its levels. In addition to food, exposure can occur through polluted air and contaminated water. Animal studies suggest that increased retention and absorption of Mn might result from iron deficiency, as both share similar physicochemical properties. However, human evidence is incomplete. This study aimed to confirm and expand upon prior findings that iron status influences Mn kinetics in the U.S. female population. The analysis included 1255 non-pregnant females aged 12-49 years with valid urinary and blood Mn and iron measurements as part of the 2015-2018 National Health and Nutrition Examination Survey. Iron status was assessed with a total body iron (TBI) score calculated from measured serum ferritin and the transferrin receptor. Iron deficiency was defined as a TBI score < 0. Demographic and laboratory characteristics (e.g. age and kidney function) were recorded. Among the study participants, roughly 8.8% were found to have iron deficiency. Conversely, 16.9% of participants exhibited blood Mn levels exceeding 1.5 µg/dL, a commonly used reference. On average, blood Mn was approximately 40% higher in subjects considered iron deficient than in their counterparts after controlling for covariates such as race. Those with iron deficiency also had a lower urine-to-blood Mn ratio. The findings suggest that iron-deficient females may have greater Mn accumulation, increasing the risk of Mn toxicity. Further investigations should include male populations to complement the current findings.

Zinc (Zn) is an essential nutrient supporting a range of critical processes. In the yeast Saccharomyces cerevisiae, Zn deficiency induces a transcriptional response mediated by the Zap1 activator, which controls a regulon of ∼80 genes. A subset support Zn homeostasis by promoting Zn uptake and its distribution between compartments, while the remainder mediate an 'adaptive response' to enhance fitness of Zn-deficient (ZnD) cells. The peroxiredoxin Tsa1 is a Zap1-regulated adaptive factor essential for the growth of ZnD yeast. Tsa1 can function as an antioxidant peroxidase, protein chaperone, or redox sensor: The latter activity oxidizes associated proteins via a redox relay mechanism. We previously reported that in ZnD cells, Tsa1 inhibits pyruvate kinase (Pyk1) to conserve phosphoenolpyruvate for aromatic amino acid synthesis. However, this regulation makes a relatively minor contribution to fitness in low Zn, suggesting that Tsa1 targets other pathways important to adaptation. Consistent with this model, the redox sensor function of Tsa1 was essential for growth of ZnD cells. Using a maltose binding protein-tagged version of Tsa1, we identified a redox-sensitive non-covalent interaction with Pyk1, and applied this system to identify multiple novel interacting partners. This interactome implicates Tsa1 in the regulation of critical processes including many Zn-dependent metabolic pathways. Interestingly, Zap1 is a Tsa1 target, as Tsa1 strongly promoted the oxidation of Zap1 activation domain 2 and was required for full Zap1 activity. Our findings reveal a novel posttranslational response to Zn deficiency, overlain on and interconnected with the Zap1-mediated transcriptional response.

The Suf pathway is the most common pathway for bacterial iron-sulfur cluster assembly and uses the SufBC2D complex as a scaffold for cluster formation. In most Gram-negative bacteria, the SufB subunit of SufBC2D accepts a persulfide from the transpersulfurase, SufE, for incorporation into nascent clusters. There is no reported structure for the SufBC2D-E complex and mechanistic details concerning the coordination of persulfide delivery with other SufBC2D activities are unclear. Using the Suf pathway from Escherichia coli as a model system, we report that SufE acts as a noncompetitive inhibitor of SufBC2D ATPase activity with a Ki value of 1.8 ± 0.2 µM. This value corresponds with a KD value of 1.6 ± 0.2 µM for SufE binding to the SufBC2D complex determined by fluorescence polarization. The rate of persulfide transfer from SufE to SufBC2D is impaired in the presence of ATP, suggesting that the two reactions are mutually exclusive. An AlphaFold3 model of the SufBC2D-E complex predicts electrostatic interactions between acidic residues on SufC and basic residues on the N-terminal helix of SufE. SufE variants at the K9 and R16 positions interfere with the ability of SufE to transfer persulfide to SufBC2D and to inhibit SufBC2D ATPase activity. In vivo complementation growth assays show that these SufE variants exhibit a slow-growth phenotype under iron starvation conditions, confirming the connection between SufE and SufC as important for optimal function in the Suf pathway. The mutual exclusivity of persulfide delivery from SufE and SufBC2D ATPase activity suggests an ordered mechanism for cluster assembly.