Deciphering the safeguarding role of cysteine residues in p53 against HO-induced oxidation using high-resolution native mass spectrometry.

The transcription factor p53 is exquisitely sensitive and selective to a broad variety of cellular environments. Several studies have reported that oxidative stress weakens the p53-DNA binding affinity for certain promoters depending on the oxidation mechanism. Despite this body of work, the precise mechanisms by which the physiologically relevant DNA-p53 tetramer complex senses cellular stresses caused by HO are still unknown.

Biarsenical-based fluorescent labeling of metallothioneins as a method for ultrasensitive quantification of poly-Cys targets.

Background: Mammalian metallothioneins (MTs) play a crucial role in maintaining Zn(II) and Cu(I) homeostasis, as well as regulating the cellular redox potential. They are involved in cancer resistance to cisplatin-related drugs and the sequestration of toxic metal ions. To investigate their participation in specific physiological and pathological processes, it is imperative to develop an analytical method for measuring changes in protein concentration both in vitro and in vivo.

An efficient and easily obtainable butelase variant for chemoenzymatic ligation and modification of peptides and proteins.

The expanding field of site-specific ligation of proteins and peptides has catalyzed the development of novel methods that enhance molecular modification. Among these methods, enzymatic strategies have emerged as dominant due to their specificity and efficiency in modifying proteins under mild conditions. Asparaginyl endopeptidase is a group of cyclotide-producing cysteine proteases from plants.

Site-Specific and Fluorescently Enhanced Installation of Post-Translational Protein Modifications via Bifunctional Biarsenical Linker.

To understand how particular post-translational modifications (PTMs) affect the function of a target protein, it is essential to first prepare and investigate the target with the modification at the desired position. This drives the continuous development of site-specific protein modification technologies. Here, we present the chemical synthesis and application of the biarsenical linker SrtCrAsH-EDT, which has a dual labeling functionality.

Analysing the accessibility of a selected southern Baltic Sea location with relevance to conducting surveys.

The article presents the accessibility conditions for carrying out research work for an exemplary site in the southern Baltic Sea region. The basic parameter of the state of the marine environment was the significant wave height determined at a frequency of one hour based on the ERA 5 model data covering the period between 1940 and 2022. A statistical analysis of the variability of this height on a monthly basis, taking into account its conversion into the time of potential availability in conditions enabling research, showed its strong seasonal variability in the form of differences in the number of hours that can be used for operating purposes.

Antioxidant-related enzymes and peptides as biomarkers of metallic nanoparticles (eco)toxicity in the aquatic environment.

Increased awareness of the impact of human activities on the environment has emerged in recent decades. One significant global environmental and human health issue is the development of materials that could potentially have negative effects. These materials can accumulate in the environment, infiltrate organisms, and move up the food chain, causing toxic effects at various levels.

Combining Native Mass Spectrometry and Proteomics to Differentiate and Map the Metalloform Landscape in Metallothioneins.

Within the intricate landscape of the proteome, approximately 30% of all proteins bind metal ions. This repertoire is even larger when considering all the different forms of a protein, known as proteoforms. Here, we propose the term "metalloforms" to refer to different structural or functional variations of a protein resulting from the binding of various hetero- or homogeneous metal ions.

Phytochelatins Bind Zn(II) with Micro- to Picomolar Affinities without the Formation of Binuclear Complexes, Exhibiting Zinc Buffering and Muffling Rather than Storing Functions.

Phytochelatins (PCs) are poly-Cys peptides containing a repeating γ-Glu-Cys motif synthesized in plants, algae, certain fungi, and worms by PC synthase from reduced glutathione. It has been shown that an excess of toxic metal ions induces their biosynthesis and that they are responsible for the detoxification process. Little is known about their participation in essential metal binding under nontoxic, basal conditions under which PC synthase is active.

Joint forces of mass spectrometric techniques (ICP-MS and MALDI-TOF-MS) and fluorescence spectrometry in the study of platinum-based cytostatic drugs interactions with metallothionein MT2 and MT3.

Herby, the interaction of metallothioneins with commonly used Pt-based anticancer drugs - cisplatin, carboplatin, and oxaliplatin - was investigated using the combined power of elemental (i.e. LA-ICP-MS, CE-ICP-MS) and molecular (i.

Small Molecule Antagonists of the DNA Repair ERCC1/XPA Protein-Protein Interaction.

The DNA excision repair protein ERCC1 and the DNA damage sensor protein, XPA are highly overexpressed in patient samples of cisplatin-resistant solid tumors including lung, bladder, ovarian, and testicular cancer. The repair of cisplatin-DNA crosslinks is dependent upon nucleotide excision repair (NER) that is modulated by protein-protein binding interactions of ERCC1, the endonuclease, XPF, and XPA. Thus, inhibition of their function is a potential therapeutic strategy for the selective sensitization of tumors to DNA-damaging platinum-based cancer therapy.

A combined biochemical and cellular approach reveals Zn-dependent hetero- and homodimeric CD4 and Lck assemblies in T cells.

The CD4 or CD8 co-receptors' interaction with the protein-tyrosine kinase Lck initiates the tyrosine phosphorylation cascade leading to T cell activation. A critical question is: to what extent are co-receptors and Lck coupled? Our contribution concerns Zn, indispensable for CD4 and CD8-Lck formation. We combined biochemical and cellular approaches to show that dynamic fluctuations of free Zn in physiological ranges influence Zn(CD4) and Zn(CD4)(Lck) species formation and their ratio, although the same Zn(Cys)(Cys) cores.

Differentiated Zn(II) binding affinities in animal, plant, and bacterial metallothioneins define their zinc buffering capacity at physiological pZn.

Metallothioneins (MTs) are small, Cys-rich proteins present in various but not all organisms, from bacteria to humans. They participate in zinc and copper metabolism, toxic metals detoxification, and protection against reactive species. Structurally, they contain one or multiple domains, capable of binding a variable number of metal ions.

Interaction patterns of methoprene-tolerant and germ cell-expressed JH receptors suggest significant differences in their functioning.

Methoprene-tolerant (Met) and germ cell-expressed (Gce) proteins were shown to be juvenile hormone (JH) receptors of with partially redundant functions. We raised the question of where the functional differentiation of paralogs comes from. Therefore, we tested Met and Gce interaction patterns with selected partners.

Structural Characterization of Cu(I)/Zn(II)-metallothionein-3 by Ion Mobility Mass Spectrometry and Top-Down Mass Spectrometry.

Mammalian zinc metallothionein-3 (ZnMT3) plays an important role in protecting against copper toxicity by scavenging free Cu(II) ions or removing Cu(II) bound to β-amyloid and α-synuclein. While previous studies reported that ZnMT3 reacts with Cu(II) ions to form Cu(I)Zn(II)MT3ox containing two disulfides (ox), the precise localization of the metal ions and disulfides remained unclear. Here, we undertook comprehensive structural characterization of the metal-protein complexes formed by the reaction between ZnMT3 and Cu(II) ions using native ion mobility mass spectrometry (IM-MS).

Calcium-assisted sortase A cleavage of SUMOylated metallothionein constructs leads to high-yield production of human MT3.

Background: Mammalian metallothioneins (MTs) are small (6-7 kDa), intracellular, cysteine-rich, metal-binding proteins involved, inter alia, in the homeostasis of zinc and copper, detoxification of heavy metals, antioxidation against reactive oxygen species, and protection against DNA damage. The high cysteine content (~ 30%) in MTs makes them toxic to bacterial cells during protein production, resulting in low yield. To address this issue, we present for the first time a combinatorial approach using the small ubiquitin-like modifier (SUMO) and/or sortase as fusion tags for high-level expression of human MT3 in E.

Nesfatin-3 possesses divalent metal ion binding properties, which remain hidden in the nucleobindin-2 precursor protein.

Background: Nucleobindin-2 (Nucb2) is a multidomain protein that, due to its structure, participates in many physiological processes. It was originally identified in several regions of the hypothalamus. However, more recent studies have redefined and extended the function of Nucb2 far beyond its initially observed role as a negative modulator of food intake.

The connection of α- and β-domains in mammalian metallothionein-2 differentiates Zn(II) binding affinities, affects folding, and determines zinc buffering properties.

Mammalian metallothioneins (MTs) are small Cys-rich proteins involved in Zn(II) and Cu(I) homeostasis. They bind seven Zn(II) ions in two distinct β- and α-domains, forming Zn3Cys9 and Zn4Cys11 clusters, respectively. After six decades of research, their role in cellular buffering of Zn(II) ions has begun to be understood recently.

From methodological limitations to the function of metallothioneins - a guide to approaches for determining weak, moderate, and tight affinity zinc sites.

Mammalian metallothioneins (MTs) are small cysteine-rich proteins whose primary role is participation in zinc and copper homeostasis. Ever since their discovery, MTs have been investigated in terms of metal-binding affinity. The initial concept of seven Zn(II) ions (Zn7MT) bound with the same, undifferentiated low-picomolar affinity in the α and β domains prevailed for many years and derived from spectroscopic studies.

Ion mobility mass spectrometry and molecular dynamics simulations unravel the conformational stability of zinc metallothionein-2 species.

Ion mobility-mass spectrometry (IM-MS) unraveled different conformational stability in Zn-metallothionein-2. We introduced a new molecular dynamics simulation approach that permitted the exploration of all of the conformational space confirming the experimental data, and revealed that not only the Zn-S bonds but also the α-β domain interactions modulate protein unfolding.

OaAEP1 Ligase-Assisted Chemoenzymatic Synthesis of Full Cysteine-Rich Metal-Binding Cyanobacterial Metallothionein SmtA.

Among all approaches used for the semisynthesis of natural or chemically modified products, enzyme-assisted ligation is among the most promising and dynamically developing approaches. Applying an efficient C247A mutant of plant ligase OaAEP1 and solid-phase peptide synthesis chemistry, we present the chemoenzymatic synthesis of a complete sequence of the cysteine-rich and metal-binding cyanobacterial metallothionein Synechococcus metallothionein A (SmtA). Zn(II) and Cd(II) binding to the newly synthesized SmtA showed identical properties to the protein expressed in .

Zn(II) to Ag(I) Swap in Rad50 Zinc Hook Domain Leads to Interprotein Complex Disruption through the Formation of Highly Stable Ag(Cys) Cores.

The widespread application of silver nanoparticles in medicinal and daily life products increases the exposure to Ag(I) of thiol-rich biological environments, which help control the cellular metallome. A displacement of native metal cofactors from their cognate protein sites is a known phenomenon for carcinogenic and otherwise toxic metal ions. Here, we examined the interaction of Ag(I) with the peptide model of the interprotein zinc hook (Hk) domain of Rad50 protein from , a key player in DNA double-strand break (DSB) repair.

One-Step Sortase-Mediated Chemoenzymatic Semisynthesis of Deubiquitinase-Resistant Ub-Peptide Conjugates.

Post-translational modifications (PTMs) of proteins increase the functional diversity of the proteome and play crucial regulatory roles in cellular processes. Ubiquitination is a highly regulated and reversible PTM accomplished by a complex multistep process with the sequential action of several specific ubiquitinating (E1-E3) and deubiquitinating enzymes. The different types of ubiquitination (mono-, poly-mono-, and poly-) and the presence of several target sites in a single substrate add to its complexity, which makes the in vitro reconstitution of this ubiquitin (Ub) machinery a quite cumbersome process.

An Overlooked Hepcidin-Cadmium Connection.

Hepcidin (DTHFPICIFCCGCCHRSKCGMCCKT), an iron-regulatory hormone, is a 25-amino-acid peptide with four intramolecular disulfide bonds circulating in blood. Its hormonal activity is indirect and consists of marking ferroportin-1 (an iron exporter) for degradation. Hepcidin biosynthesis involves the N-terminally extended precursors prepro-hepcidin and pro-hepcidin, processed by peptidases to the final 25-peptide form.

Non-Conserved Amino Acid Residues Modulate the Thermodynamics of Zn(II) Binding to Classical ββα Zinc Finger Domains.

Classical zinc fingers domains (ZFs) bind Zn(II) ion by a pair of cysteine and histidine residues to adopt a characteristic and stable ββα fold containing a small hydrophobic core. As a component of transcription factors, they recognize specific DNA sequences to transcript particular genes. The loss of Zn(II) disrupts the unique structure and function of the whole protein.

An Extremely Stable Interprotein Tetrahedral Hg(Cys) Core Forms in the Zinc Hook Domain of Rad50 Protein at Physiological pH.

Invited for the cover of this issue is the group of Artur Krężel at the University of Wrocław in collaboration with Lars Hemmingsen at The University of Copenhagen and Eva Freisinger at the University of Zürich. The image depicts the outcomes of Hg interactions with Rad50 protein. Read the full text of the article at 10.