1.
Tjondro, Harry C., et al.
(författare)
Hyper-truncated Asn355- And Asn391-glycans modulate the activity of neutrophil granule myeloperoxidase
2021
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 296
Tidskriftsartikel (refereegranskat) abstract
Myeloperoxidase (MPO) plays essential roles in neutrophil-mediated immunity via the generation of reactive oxidation products. Complex carbohydrates decorate MPO at discrete sites, but their functional relevance remains elusive. To this end, we have characterised the structure–biosynthesis–activity relationship of neutrophil MPO (nMPO). Mass spectrometry demonstrated that nMPO carries both characteristic under-processed and hyper-truncated glycans. Occlusion of the Asn355/Asn391-glycosylation sites and the Asn323-/Asn483-glycans, located in the MPO dimerisation zone, was found to affect the local glycan processing, thereby providing a molecular basis of the site-specific nMPO glycosylation. Native mass spectrometry, mass photometry and glycopeptide profiling revealed significant molecular complexity of diprotomeric nMPO arising from heterogeneous glycosylation, oxidation, chlorination and polypeptide truncation variants and a previously unreported low-abundance monoprotomer. Longitudinal profiling of maturing, mature, granule-separated and pathogen-stimulated neutrophils demonstrated that nMPO is dynamically expressed during granulopoiesis, unevenly distributed across granules and degranulated upon activation. We also show that proMPO-to-MPO maturation occurs during early/mid-stage granulopoiesis. While similar global MPO glycosylation was observed across conditions, the conserved Asn355-/Asn391-sites displayed elevated glycan hyper-truncation, which correlated with higher enzyme activities of MPO in distinct granule populations. Enzymatic trimming of the Asn355-/Asn391-glycans recapitulated the activity gain and showed that nMPO carrying hyper-truncated glycans at these positions exhibits increased thermal stability, polypeptide accessibility and ceruloplasmin-mediated inhibition potential relative to native nMPO. Finally, molecular modelling revealed that hyper-truncated Asn355-glycans positioned in the MPO-ceruloplasmin interface are critical for uninterrupted inhibition. Here, through an innovative and comprehensive approach, we report novel functional roles of MPO glycans, providing new insight into neutrophil-mediated immunity.
2.
Landberg, Rikard, 1981, et al.
(författare)
Avenanthramides as lipoxygenase inhibitors
2020
Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 6:6
Tidskriftsartikel (refereegranskat) abstract
Avenanthramides (AVAs) present in oats are amides of anthranilic and cinnamic acids. AVAs are potent antioxidants and have anti-inflammatory properties. There are various potential mechanisms for their anti-inflammatory effects, including inhibition of lipoxygenases (LOX), which catalyse oxygenation of polyunsaturated fatty acids into potent signal molecules involved in inflammatory processes. In this study, AVAs were screened for LOX inhibition in vitro and structure-activity relationships were examined. Twelve different AVAs at 0.6 mM were tested as LOX inhibitors. The corresponding free cinnamic acids, the AVA analogue Tranilast® and the known LOX inhibitor trans-resveratrol were included for comparison. It was found that AVAs comprising caffeic or sinapic acid exhibited significant lipoxygenase inhibition (60–90%) (P < 0.05), whereas low or no inhibition was observed with AVAs containing p-coumaric or ferulic acid. No difference in inhibition was seen on comparing AVAs with their free corresponding cinnamic acids, which implies that the anthranilic acid part of the avenanthramide molecule does not affect inhibition. Trans-resveratrol showed inhibition, whereas no inhibition was seen for Tranilast® at the concentrations used in this study. This study suggests that aventahtramides comprising caffeic acid or sinapic acid partly exert their antioxidant and anti-inflammatory effects via lipoxygenase inhibition.
3.
Bally, Marta, 1981, et al.
(författare)
Physicochemical tools for studying virus interactions with targeted cell membranes in a molecular and spatiotemporally resolved context
2021
Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 413
Tidskriftsartikel (refereegranskat) abstract
The objective of this critical review is to provide an overview of how emerging bioanalytical techniques are expanding our understanding of the complex physicochemical nature of virus interactions with host cell surfaces. Herein, selected model viruses representing both non-enveloped (simian virus 40 and human norovirus) and enveloped (influenza A virus, human herpes simplex virus, and human immunodeficiency virus type 1) viruses are highlighted. The technologies covered utilize a wide range of cell membrane mimics, from supported lipid bilayers (SLBs) containing a single purified host membrane component to SLBs derived from the plasma membrane of a target cell, which can be compared with live-cell experiments to better understand the role of individual interaction pairs in virus attachment and entry. These platforms are used to quantify binding strengths, residence times, diffusion characteristics, and binding kinetics down to the single virus particle and single receptor, and even to provide assessments of multivalent interactions. The technologies covered herein are surface plasmon resonance (SPR), quartz crystal microbalance with dissipation (QCM-D), dynamic force spectroscopy (DFS), total internal reflection fluorescence (TIRF) microscopy combined with equilibrium fluctuation analysis (EFA) and single particle tracking (SPT), and finally confocal microscopy using multi-labeling techniques to visualize entry of individual virus particles in live cells. Considering the growing scientific and societal needs for untangling, and interfering with, the complex mechanisms of virus binding and entry, we hope that this review will stimulate the community to implement these emerging tools and strategies in conjunction with more traditional methods. The gained knowledge will not only contribute to a better understanding of the virus biology, but may also facilitate the design of effective inhibitors to block virus entry.
4.
Kallas, Pawel, et al.
(författare)
Adhesion of Escherichia Coli to Nanostructured Surfaces and the Role of Type 1 Fimbriae
2020
Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:11
Tidskriftsartikel (refereegranskat) abstract
Bacterial fimbriae are an important virulence factor mediating adhesion to both biotic and abiotic surfaces and facilitating biofilm formation. The expression of type 1 fimbriae of Escherichia coli is a key virulence factor for urinary tract infections and catheter-associated urinary tract infections, which represent the most common nosocomial infections. New strategies to reduce adhesion of bacteria to surfaces is therefore warranted. The aim of the present study was to investigate how surfaces with different nanotopography-influenced fimbriae-mediated adhesion. Surfaces with three different nanopattern surface coverages made in polycarbonate were fabricated by injection molding from electron beam lithography nanopatterned templates. The surfaces were constructed with features of approximately 40 nm width and 25 nm height with 100 nm, 250 nm, and 500 nm interspace distance, respectively. The role of fimbriae type 1-mediated adhesion was investigated using the E. coli wild type BW25113 and Delta fimA (with a knockout of major pilus protein FimA) and Delta fimH (with a knockout of minor protein FimH) mutants. For the surfaces with nanotopography, all strains adhered least to areas with the largest interpillar distance (500 nm). For the E. coli wild type, no difference in adhesion between surfaces without pillars and the largest interpillar distance was observed. For the deletion mutants, increased adhesion was observed for surfaces without pillars compared to surfaces with the largest interpillar distance. The presence of a fully functional type 1 fimbria decreased the bacterial adhesion to the nanopatterned surfaces in comparison to the mutants.
5.
Chen, Yu, 1990, et al.
(författare)
Yeast optimizes metal utilization based on metabolic network and enzyme kinetics
2021
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 118:12
Tidskriftsartikel (refereegranskat) abstract
Metal ions are vital to metabolism, as they can act as cofactors on enzymes and thus modulate individual enzymatic reactions. Although many enzymes have been reported to interact with metal ions, the quantitative relationships between metal ions and metabolism are lacking. Here, we reconstructed a genome-scale metabolic model of the yeast Saccharomyces cerevisiae to account for proteome constraints and enzyme cofactors such as metal ions, named CofactorYeast. The model is able to estimate abundances of metal ions binding on enzymes in cells under various conditions, which are comparable to measured metal ion contents in biomass. In addition, the model predicts distinct metabolic flux distributions in response to reduced levels of various metal ions in the medium. Specifically, the model reproduces changes upon iron deficiency in metabolic and gene expression levels, which could be interpreted by optimization principles (i.e., yeast optimizes iron utilization based on metabolic network and enzyme kinetics rather than preferentially targeting iron to specific enzymes or pathways). At last, we show the potential of using the model for understanding cell factories that harbor heterologous iron-containing enzymes to synthesize high-value compounds such as p-coumaric acid. Overall, the model demonstrates the dependence of enzymes on metal ions and links metal ions to metabolism on a genome scale.
6.
Ghirmai, Semhar, 1993, et al.
(författare)
Improving the Stability of Red Blood Cells in Rainbow Trout (Oncorhynchus mykiss) and Herring (Clupea harengus): Potential Solutions for Post-mortem Fish Handling to Minimize Lipid Oxidation
2020
Ingår i: Food and Bioprocess Technology. - : Springer Science and Business Media LLC. - 1935-5130 .- 1935-5149. ; 13
Tidskriftsartikel (refereegranskat) abstract
This study aimed at limiting hemolysis of fish red blood cells (RBCs) as a strategy to limit hemoglobin (Hb)-induced lipid oxidation duringpost-mortemhandling and processing. Effects of varying temperature, salinity, and mechanical impact were studied using washed resuspended RBCs (wr-RBCs) and whole blood (WB) from rainbow trout (Oncorhynchus mykiss) and herring (Clupea harengus). The wr-RBCs were most stable avoiding mechanical stress, keeping isotonic conditions (0.9-1.3% NaCl) and low temperature 0-6 degrees C, with predicted minimum at 2.5 degrees C. When compared at the same salinity, it was found that hemolysis was more pronounced in herring than trout wr-RBCs. Furthermore, WB was more stable than wr-RBCs, showing protecting the effects of blood plasma. Studying individual plasma components, stabilizing effects were found from glucose, proteins, and ascorbic acid. This study indicates that small adjustments in the early handling and processing of fish such as changing salinity of storage and rinsing solutions could minimize Hb contamination of the fish muscle and thereby improve quality.
7.
McStay, Natasha, et al.
(författare)
Click and Cut: a click chemistry approach to developing oxidative DNA damaging agents
2021
Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 49:18, s. 10289-10308
Tidskriftsartikel (refereegranskat) abstract
Metallodrugs provide important first-line treatment against various forms of human cancer. To overcome chemotherapeutic resistance and widen treatment possibilities, new agents with improved or alternative modes of action are highly sought after. Here, we present a click chemistry strategy for developing DNA damaging metallodrugs. The approach involves the development of a series of polyamine ligands where three primary, secondary or tertiary alkyne-amines were selected and 'clicked' using the copper-catalysed azide-alkyne cycloaddition reaction to a 1,3,5-azide mesitylene core to produce a family of compounds we call the 'Tri-Click' (TC) series. From the isolated library, one dominant ligand (TC1) emerged as a high-affinity copper(II) binding agent with potent DNA recognition and damaging properties. Using a range of in vitro biophysical and molecular techniques-including free radical scavengers, spin trapping antioxidants and base excision repair (BER) enzymes-the oxidative DNA damaging mechanism of copper-bound TC1 was elucidated. This activity was then compared to intracellular results obtained from peripheral blood mononuclear cells exposed to Cu(ll)-TC1 where use of BER enzymes and fluorescently modified dNTPs enabled the characterisation and quantification of genomic DNA lesions produced by the complex. The approach can serve as a new avenue for the design of DNA damaging agents with unique activity profiles.
8.
Venkatakrishnan, Vignes, et al.
(författare)
Glycan analysis of human neutrophil granules implicates a maturation-dependent glycosylation machinery
2020
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:36, s. 12648-12660
Tidskriftsartikel (refereegranskat) abstract
Protein glycosylation is essential to trafficking and immune functions of human neutrophils. During granulopoiesis in the bone marrow, distinct neutrophil granules are successively formed. Distinct receptors and effector proteins, many of which are glycosylated, are targeted to each type of granule according to their time of expression, a process called "targeting by timing." Therefore, these granules are time capsules reflecting different times of maturation that can be used to understand the glycosylation process during granulopoiesis. Herein, neutrophil subcellular granules were fractionated by Percoll density gradient centrifugation, andN- andO-glycans present in each compartment were analyzed by LC-MS. We found abundant paucimannosidicN-glycans and lack ofO-glycans in the early-formed azurophil granules, whereas the later-formed specific and gelatinase granules and secretory vesicles contained complexN-andO-glycans with remarkably elongatedN-acetyllactosamine repeats with Lewis epitopes. Immunoblotting and histochemical analysis confirmed the expression of Lewis X and sialyl-Lewis X in the intracellular granules and on the cell surface, respectively. Many glycans identified are unique to neutrophils, and their complexity increased progressively from azurophil granules to specific granules and then to gelatinase granules, suggesting temporal changes in the glycosylation machinery indicative of "glycosylation by timing" during granulopoiesis. In summary, this comprehensive neutrophil granule glycome map, the first of its kind, highlights novel granule-specific glycosylation features and is a crucial first step toward a better understanding of the mechanisms regulating protein glycosylation during neutrophil granulopoiesis and a more detailed understanding of neutrophil biology and function.
9.
Esmaily, Mohsen, 1987, et al.
(författare)
Oxidation and electrical properties of chromium–iron alloys in a corrosive molten electrolyte environment
2020
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10, s. 1-19
Tidskriftsartikel (refereegranskat) abstract
Chromium–iron (CrFe) binary alloys have recently been proposed to serve as the “inert” anode for molten oxide electrolysis (MOE). Herein, the effects of anodic polarization on physical and functional properties of CrFe anodes in the corrosive environment of MOE are studied via empirical observations and theoretical calculations. The findings indicate that the alloys form an inner chromia–alumina solid-solution covered by an MgCr2O4 spinel layer. A survey into the electrical properties of the detected oxides suggests that the layered oxide scale function as an efficient conductor of electricity at elevated temperature. The formation mechanism of the oxides is also investigated.
10.
Gupta, Swarnim, 1984, et al.
(författare)
The development of a novel ferric phytate compound for iron fortification of bouillons (part I)
2020
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 10:1
Tidskriftsartikel (refereegranskat) abstract
In a series of two studies, we report the development (this study) and evaluation (part II) of a novel ferric phytate compound designed as a condiment iron fortificant. Condiments are used as iron fortification vehicles to reduce the prevalence of iron deficiency. The challenge for iron fortificants in e.g. a bouillon matrix is to avoid undesired sensory effects and to ensure a reasonable cost. We added phytic acid to chelate iron, and hydrolysed protein to counteract the inhibiting effect of phytic acid on iron bioaccessibility. We characterised four novel ferric phytate compounds, destabilised by hydrolysed plant protein or amino acids. Colour stability of fortified bouillons with ferric phytate compounds was superior to bouillons fortified with ferrous sulfate. The iron-phytate-hydrolysed corn protein compound (Fe-PAHCP) resulted in highest cellular ferritin induction in Caco-2 cells, in both vegetable (36.1 ± 13.40 ng/mg protein) and chicken (73.9 ± 19.93 ng/mg protein) bouillon matrices as observed in the human Caco-2/ HepG2 cell model. Iron uptake (as estimated by ferritin production) from the Fe-PA-HCP compound was about 55% (chicken bouillon) and 66% (vegetable bouillon) of the iron uptake from ferrous sulfate. Based on this study, the Fe-PA-HCP compound was chosen for further evaluation (part II).
