Identification of Novel Human 15-Lipoxygenase-2 (h15-LOX-2) Inhibitors Using a Virtual Screening Approach.

The human 15-lipoxygenase-2 (h15-LOX-2) catalyzes mainly the regio- and stereospecific oxygenation of arachidonate to its corresponding hydroperoxide (15()-HpETE). h15-LOX-2 is implicated in the biosynthesis of inflammatory lipid mediators and plays a role in the development of atherosclerotic plaques, but it is still underexploited as a drug target. Here, to search for novel h15-LOX-2 inhibitors, we used a virtual screening (VS) approach consisting of shape-based matching, two-dimensional (2D) structural "dissimilarity", docking, and visual inspection filters, which were applied to a "curated" ZINC database (∼8 × 10 compounds).

Human mitochondrial peroxiredoxin Prdx3 is dually localized in the intermembrane space and matrix subcompartments.

Peroxiredoxin 3 (Prdx3) is the major sink for HO and other hydroperoxides within mitochondria, yet the mechanisms guiding the import of its cytosolic precursor into mitochondrial sub-compartments remain elusive. Prdx3 is synthesized in the cytosol as a precursor with an N-terminal cleavable presequence, which is frequently proposed to target the protein exclusively to the mitochondrial matrix. Here, we present a comprehensive analysis of the human Prdx3 biogenesis, using highly purified mitochondria from HEK293T cells.

PRDX6 contributes to selenocysteine metabolism and ferroptosis resistance.

Selenocysteine (Sec) metabolism is crucial for cellular function and ferroptosis prevention and begins with the uptake of the Sec carrier, selenoprotein P (SELENOP). Following uptake, Sec released from SELENOP is metabolized via selenocysteine lyase (SCLY), producing selenide, a substrate for selenophosphate synthetase 2 (SEPHS2), which provides the essential selenium donor, selenophosphate (HSePO), for the biosynthesis of the Sec-tRNA. Here, we discovered an alternative pathway in Sec metabolism mediated by peroxiredoxin 6 (PRDX6), independent of SCLY.

On the binding of auranofin to Prdx6 and its potential role in cancer cell sensitivity to treatment.

In this study, we demonstrate that ferroptosis is a component of the cell death mechanism induced by auranofin in HT-1080 cells, in contrast to the gold(III) compounds [Au(phen)Cl]PF and [Au(bnpy)Cl]. Additionally, we identify a potential role of Prdx6 in modulating the sensitivity of A-375 cells to auranofin treatment, whereas the gold(III) compounds evaluated here exhibit Prdx6-independent cytotoxicity. Finally, using mass spectrometry, we show that auranofin binds selectively to the catalytic Cys47 residue of Prdx6 in vitro under acidic conditions.

PRDX6 contributes to selenocysteine metabolism and ferroptosis resistance.

Selenocysteine (Sec) metabolism is crucial for cellular function and ferroptosis prevention and has traditionally been thought to begin with the uptake of the Sec carrier selenoprotein P (SELENOP). Following uptake, Sec released from SELENOP undergoes metabolisation via selenocysteine lyase (SCLY), producing selenide, a substrate used by selenophosphate synthetase 2 (SEPHS2), which provides the essential selenium donor - selenophosphate - for the biosynthesis of the selenocysteine tRNA. Here, we report the discovery of an alternative pathway mediating Sec metabolisation that is independent of SCLY and mediated by peroxiredoxin 6 (PRDX6).

Functional diversity of YbbN/CnoX proteins: Insights from a comparative analysis of three thioredoxin-like oxidoreductases from Pseudomonas aeruginosa, Xylella fastidiosa and Escherichia coli.

YbbN/CnoX are proteins that display a Thioredoxin (Trx) domain linked to a tetratricopeptide domain. YbbN from Escherichia coli (EcYbbN) displays a co-chaperone (holdase) activity that is induced by HOCl. Here, we compared EcYbbN with YbbN proteins from Xylella fastidiosa (XfYbbN) and from Pseudomonas aeruginosa (PaYbbN).

Severe COVID-19 patients show a dysregulation of the NLRP3 inflammasome in circulating neutrophils.

SARS-CoV-2 triggers inflammasome-dependent release of pro-inflammatory cytokine IL-1β and pyroptosis, therefore, contributes to the huge inflammatory response observed in severe COVID-19 patients. Less is known about the engagement of inflammasome in neutrophils, main players in tissue injury and severe infection. We studied the activation of the inflammasome in neutrophils from severe COVID-19 patients and assessed its consequence in term of cells contribution to disease pathogenesis.

A common variant close to the "tripwire" linker region of NLRP1 contributes to severe COVID-19.

Objective And Design: The heterogeneity of response to SARS-CoV-2 infection is directly linked to the individual genetic background. Genetic variants of inflammasome-related genes have been pointed as risk factors for several inflammatory sterile and infectious disease. In the group of inflammasome receptors, NLRP1 stands out as a good novel candidate as severity factor for COVID-19 disease.

Absence of Gem1 (mammalian Miro/Rhot) mitigates alpha-synuclein toxicity in a yeast model of Parkinson's disease.

Alpha-synuclein aggregation is a hallmark of Parkinson's disease (PD). Mutants A30P and A53T alpha-synuclein are known to exacerbate the toxicity of alpha-synuclein, which includes oxidative stress, mitochondrial and endoplasmic reticulum (ER) dysfunction. Saccharomyces cerevisiae (budding yeast) is a cellular model widely used to investigate mechanisms underlying neurodegenerative disorders, such as PD.

Adenanthin Is an Efficient Inhibitor of Peroxiredoxins from Pathogens, Inhibits Bacterial Growth, and Potentiates Antibiotic Activities.

The emergence and re-emergence of bacterial strains resistant to multiple drugs represent a global health threat, and the search for novel biological targets is a worldwide concern. AhpC are enzymes involved in bacterial redox homeostasis by metabolizing diverse kinds of hydroperoxides. In pathogenic bacteria, AhpC are related to several functions, as some isoforms are characterized as virulence factors.

Preferential redox regulation of cysteine-based protein tyrosine phosphatases: structural and biochemical diversity.

Protein phosphorylation is a major post-translational modification involved in cell signalling that regulates many physiological and pathological processes. Despite their biological importance, protein phosphatases are less studied than protein kinases. Importantly, the activity of Cys-based protein tyrosine phosphatases (PTPs) can be regulated by reversible oxidation.

Ohr - OhrR, a neglected and highly efficient antioxidant system: Structure, catalysis, phylogeny, regulation, and physiological roles.

Ohrs (organic hydroperoxide resistance proteins) are antioxidant enzymes that play central roles in the response of microorganisms to organic peroxides. Here, we describe recent advances in the structure, catalysis, phylogeny, regulation, and physiological roles of Ohr proteins and of its transcriptional regulator, OhrR, highlighting their unique features. Ohr is extremely efficient in reducing fatty acid peroxides and peroxynitrite, two oxidants relevant in host-pathogen interactions.

Safety and immunogenicity of CoronaVac in people living with HIV: a prospective cohort study.

Background: People living with HIV might have a poor or delayed response to vaccines, mainly when CD4 cell counts are low, and data concerning COVID-19 vaccines in this population are scarce. This prospective cohort study assessed the safety and immunogenicity of the inactivated SARS-CoV-2 vaccine CoronaVac in people with HIV compared with people with no known immunosuppression.

Methods: In this prospective cohort study, adults (aged ≥18 years) living with HIV who were regularly followed up at the University of Sao Paulo HIV/AIDS outpatient clinic in Sao Paulo, Brazil, were included in the study.

Dissecting the molecular mechanisms of mitochondrial import and maturation of peroxiredoxins from yeast and mammalian cells.

Peroxiredoxins (Prxs) are cysteine-based peroxidases that play a central role in keeping the HO at physiological levels. Eukaryotic cells express different Prxs isoforms, which differ in their subcellular locations and substrate specificities. Mitochondrial Prxs are synthesized in the cytosol as precursor proteins containing N-terminal cleavable presequences that act as mitochondrial targeting signals.

Drugs age-of-onset as a signal of later post-traumatic stress disorder: Bayesian analysis of a census protocol.

Individuals with PTSD have an increased risk of drug use disorders. Conversely, we aim to evaluate how early onset of alcohol, tobacco and psychoactive drugs use are associated with PTSD later in life. 2,193 brazilian young adults completed modularized assessments: The Trauma History Questionnaire, Post-Traumatic Stress Disorder Checklist-Civilian Version (PCL-C, transformed to PCL-5 through a crosswalk procedure), the Barratt Impulsivity Scale; and a survey on drug use with self-report questions about first use, current use, frequency, quantity, and interpersonal consequences.

Coq3p relevant residues for protein activity and stability.

Coenzyme Q (CoQ) is an essential molecule that consists of a highly substituted benzene ring attached to a polyprenyl tail anchored in the inner mitochondrial membrane. CoQ transfers electrons from NADH dehydrogenase and succinate dehydrogenase complexes toward ubiquinol-cytochrome c reductase, and that allows aerobic growth of cells. In Saccharomyces cerevisiae, the synthesis of CoQ depends on fourteen proteins Coq1p-Co11p, Yah1p, Arh1p, and Hfd1p.

Assessment of Submitochondrial Protein Localization in Budding Yeast Saccharomyces cerevisiae.

Despite recent advances in the characterization of yeast mitochondrial proteome, the submitochondrial localization of a significant number of proteins remains elusive. Here, we describe a robust and effective method for determining the suborganellar localization of yeast mitochondrial proteins, which is considered a fundamental step during mitochondrial protein function elucidation. This method involves an initial step that consists of obtaining highly pure intact mitochondria.

Peroxiredoxin AhpC1 protects Pseudomonas aeruginosa against the inflammatory oxidative burst and confers virulence.

Pseudomonas aeruginosa is an opportunistic bacterium in patients with cystic fibrosis and hospital acquired infections. It presents a plethora of virulence factors and antioxidant enzymes that help to subvert the immune system. In this study, we identified the 2-Cys peroxiredoxin, alkyl-hydroperoxide reductase C1 (AhpC1), as a relevant scavenger of oxidants generated during inflammatory oxidative burst and a mechanism of P.

Relevance of peroxiredoxins in pathogenic microorganisms.

The oxidative and nitrosative responses generated by animals and plants are important defenses against infection and establishment of pathogenic microorganisms such as bacteria, fungi, and protozoa. Among distinct oxidant species, hydroperoxides are a group of chemically diverse compounds that comprise small hydrophilic molecules, such as hydrogen peroxide and peroxynitrite, and bulky hydrophobic species, such as organic hydroperoxides. Peroxiredoxins (Prx) are ubiquitous enzymes that use a highly reactive cysteine residue to decompose hydroperoxides and can also perform other functions, like molecular chaperone and phospholipase activities, contributing to microbial protection against the host defenses.

Effects of Serine or Threonine in the Active Site of Typical 2-Cys Prx on Hyperoxidation Susceptibility and on Chaperone Activity.

Typical 2-Cys peroxiredoxins (2-Cys Prx) are ubiquitous Cys-based peroxidases, which are stable as decamers in the reduced state, and may dissociate into dimers upon disulfide bond formation. A peroxidatic Cys (C) takes part of a catalytic triad, together with a Thr/Ser and an Arg. Previously, we described that the presence of Ser (instead of Thr) in the active site stabilizes yeast 2-Cys Prx as decamers.

Oxidative Modification of Proteins: From Damage to Catalysis, Signaling, and Beyond.

The systematic investigation of oxidative modification of proteins by reactive oxygen species started in 1980. Later, it was shown that reactive nitrogen species could also modify proteins. Some protein oxidative modifications promote loss of protein function, cleavage or aggregation, and some result in proteo-toxicity and cellular homeostasis disruption.

Molecular Structure and Functional Analysis of Pyocin S8 from Pseudomonas aeruginosa Reveals the Essential Requirement of a Glutamate Residue in the H-N-H Motif for DNase Activity.

Multidrug resistance (MDR) is a serious threat to public health, making the development of new antimicrobials an urgent necessity. Pyocins are protein antibiotics produced by strains to kill closely related cells during intraspecific competition. Here, we report an in-depth biochemical, microbicidal, and structural characterization of a new S-type pyocin, named S8.

The Aspergillus fumigatus transcription factor RglT is important for gliotoxin biosynthesis and self-protection, and virulence.

Aspergillus fumigatus is an opportunistic fungal pathogen that secretes an array of immune-modulatory molecules, including secondary metabolites (SMs), which contribute to enhancing fungal fitness and growth within the mammalian host. Gliotoxin (GT) is a SM that interferes with the function and recruitment of innate immune cells, which are essential for eliminating A. fumigatus during invasive infections.