Antimicrobial Nodule-Specific Cysteine-Rich Peptides Induce Membrane Depolarization-Associated Changes in the Transcriptome of Sinorhizobium meliloti.

Leguminous plants establish symbiosis with nitrogen-fixing alpha- and betaproteobacteria, collectively called rhizobia, which provide combined nitrogen to support plant growth. Members of the inverted repeat-lacking clade of legumes impose terminal differentiation on their endosymbiotic bacterium partners with the help of the nodule-specific cysteine-rich (NCR) peptide family composed of close to 600 members. Among the few tested NCR peptides, cationic ones had antirhizobial activity measured by reduction or elimination of the CFU and uptake of the membrane-impermeable dye propidium iodide. Here, the antimicrobial spectrum of two of these peptides, NCR247 and NCR335, was investigated, and their effect on the transcriptome of the natural target Sinorhizobium meliloti was characterized. Both peptides were able to kill quickly a wide range of Gram-negative and Gram-positive bacteria; however, their spectra were only partially overlapping, and differences were found also in their efficacy on given strains, indicating that the actions of NCR247 and NCR335 might be similar though not identical. Treatment of S. meliloti cultures with either peptide resulted in a quick downregulation of genes involved in basic cellular functions, such as transcription-translation and energy production, as well as upregulation of genes involved in stress and oxidative stress responses and membrane transport. Similar changes provoked mainly in Gram-positive bacteria by antimicrobial agents were coupled with the destruction of membrane potential, indicating that it might also be a common step in the bactericidal actions of NCR247 and NCR335

Національні тенденції розвитку університетської освіти

В сучасному динамічно змінюваному світі університет - це перш за все вищий навчальний заклад, який є індикатором цивілізаційності регіону та держави. Проте у наші дні класичні університети постали перед серйозними викликами часу.В современном динамически изменяющемся мире университет - это прежде всего высшее учебное заведение, которое является индикатором цивилизационности региона и государства. Однако в наши дни классические университеты встали перед серьезными вызовами времени

Філософія популізму як варіант сучасної філософії

We have previously reported on the functional interaction of Lipid II with human alpha-defensins, a class of antimicrobial peptides. Lipid II is an essential precursor for bacterial cell wall biosynthesis and an ideal and validated target for natural antibiotic compounds. Using a combination of structural, functional and in silico analyses, we present here the molecular basis for defensin-Lipid II binding. Based on the complex of Lipid II with Human Neutrophil peptide-1, we could identify and characterize chemically diverse low-molecular weight compounds that mimic the interactions between HNP-1 and Lipid II. Lead compound BAS00127538 was further characterized structurally and functionally; it specifically interacts with the N-acetyl muramic acid moiety and isoprenyl tail of Lipid II, targets cell wall synthesis and was protective in an in vivo model for sepsis. For the first time, we have identified and characterized low molecular weight synthetic compounds that target Lipid II with high specificity and affinity. Optimization of these compounds may allow for their development as novel, next generation therapeutic agents for the treatment of Gram-positive pathogenic infections

Enhanced Membrane Pore Formation through High-Affinity Targeted Antimicrobial Peptides

Many cationic antimicrobial peptides (AMPs) target the unique lipid composition of the prokaryotic cell membrane. However, the micromolar activities common for these peptides are considered weak in comparison to nisin, which follows a targeted, pore-forming mode of action. Here we show that AMPs can be modified with a high-affinity targeting module, which enables membrane permeabilization at low concentration. Magainin 2 and a truncated peptide analog were conjugated to vancomycin using click chemistry, and could be directed towards specific membrane embedded receptors both in model membrane systems and whole cells. Compared with untargeted vesicles, a gain in permeabilization efficacy of two orders of magnitude was reached with large unilamellar vesicles that included lipid II, the target of vancomycin. The truncated vancomycin-peptide conjugate showed an increased activity against vancomycin resistant Enterococci, whereas the full-length conjugate was more active against a targeted eukaryotic cell model: lipid II containing erythrocytes. This study highlights that AMPs can be made more selective and more potent against biological membranes that contain structures that can be targeted

Resistance of Gram-positive bacteria to nisin is not determined by Lipid II levels

Lipid II is essential for nisin-mediated pore formation at nano-molar concentrations. We tested whether nisin resistance could result from different Lipid II levels, by comparing the maximal Lipid II pool in Micrococcus flavus (sensitive) and Listeria monocytogenes (relatively insensitive) and their nisin-resistant variants, with a newly developed method. No correlation was observed between the maximal Lipid II pool and nisin sensitivity, as was further corroborated by using spheroplasts of nisin-resistant and wild-type strains of M. flavus, which were equally sensitive to nisin. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved

Docking and molecular dynamics simulations of the ternary complex nisin2:lipid II

Lanthionine antibiotics are an important class of naturally-occurring antimicrobial peptides. The best-known, nisin, is a commercial food preservative. However, structural and mechanistic details on nisin/lipid II membrane complexes are currently lacking. Recently, we have developed empirical force-field parameters to model lantibiotics. Docking and molecular dynamics (MD) simulations have been used to study the nisin2:lipid II complex in bacterial membranes, which has been put forward as the building block of nisin/lipid II binary membrane pores. A Ile1Trp mutation of the N-terminus of nisin has been modelled and docked onto lipid II models; the computed binding affinity increased compared to wildtype. Wild-type nisin was also docked onto three different lipid II structures and a stable 2:1 nisin:lipid II complex formed. This complex was inserted into a membrane. Six independent MD simulations revealed key interactions in the complex, specifically the N terminal engagement of nisin with lipid II at the pyrophosphate and C-terminus of the pentapeptide chain. Nisin2 inserts into the membrane and we propose this is the first step in pore formation, mediated by the nisin N-terminus–lipid II pentapeptide hydrogen bond. The lipid II undecaprenyl chain adopted different conformations in the presence of nisin, which may also have implications for pore formation

Development of teixobactin analogues containing hydrophobic, non-proteogenic amino acids that are highly potent against multidrug-resistant bacteria and biofilms

Teixobactin is a cyclic undecadepsipeptide that has shown excellent potency against multidrug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). In this article, we present the design, synthesis, and antibacterial evaluations of 16 different teixobactin analogues. These simplified analogues contain commercially available hydrophobic, non-proteogenic amino acid residues instead of synthetically challenging expensive L-allo-enduracididine amino acid residue at position 10 together with different combinations of arginines at positions 3, 4 and 9. The new teixobactin analogues showed potent antibacterial activity against a broad panel of Gram-positive bacteria, including MRSA and VRE strains. Our work also presents the first demonstration of the potent antibiofilm activity of teixobactin analogoues against Staphylococcus species associated with serious chronic infections. Our results suggest that the use of hydrophobic, non-proteogenic amino acids at position 10 in combination with arginine at positions 3, 4 and 9 holds the key to synthesising a new generation of highly potent teixobactin analogues to tackle resistant bacterial infections and biofilms

Bacillus subtilis MraY in detergent-free system of nanodiscs wrapped by styrene-maleic acid copolymers

As an integral membrane protein, purification and characterization of phospho-N-acetyl-muramyl-pentapeptide translocase MraY have proven difficult. Low yield and concerns of retaining stability and activity after detergent solubilization have hampered the structure-function analysis. The recently developed detergent-free styrene-maleic acid (SMA) copolymer system offers an alternative approach that may overcome these disadvantages. In this study, we used the detergent free system to purify MraY from Bacillus subtilis. This allowed efficient extraction of MraY that was heterologously produced in Escherichia coli membranes into SMA-wrapped nanodiscs. The purified MraY embedded in these nanodiscs (SMA-MraY) was comparable to the micellar MraY extracted with a conventional detergent (DDM) with regard to the yield and the purity of the recombinant protein but required significantly less time. The predominantly alpha-helical secondary structure of the protein in SMA-wrapped nanodiscs was also more stable against heat denaturation compared to the micellar protein. Thus, this detergent-free system is amenable to extract MraY efficiently and effectively while maintaining the biophysical properties of the protein. However, the apparent activity of the SMA-MraY was reduced compared to that of the detergent-solubilized protein. The present data indicates that this is caused by a lower accessibility of the enzyme in SMA-wrapped nanodiscs towards its polyisoprenoid substrate

Vitale vennootschappen in veilige handen

The research looked in particular at the question of how ownership in a Dutch public limited company or private limited company may (possibly) provide access to (confidential) information and influence decision-making, and how this may impact national security. The following vital sectors are discussed: energy, ICT/Telecom, drinking water and water, transport, the chemical industry, the nuclear sector, the financial sector, digital government and Defence. Het komt geregeld voor dat buitenlandse investeerders belangrijke aandeelhoudersrechten in Nederlandse ondernemingen verwerven of trachten te verwerven. Buitenlandse investeringen leveren een materiële bijdrage aan de Nederlandse welvaart. Niettemin komt in de huidige geopolitieke context de vraag op of buitenlands aandeelhouderschap tevens een bedreiging kan vormen voor Nederlandse (publieke) belangen. De vraag is 'wat zijn de risico’s van (buitenlands) aandeelhouderschap voor de nationale veiligheid'? In dit onderzoek staat de vraag centraal hoe aandeelhouderschap in een Nederlandse naamloze of besloten vennootschap (mogelijke) toegang tot (vertrouwelijke) informatie en invloed op beslissingen biedt en op welke wijze dit gevolgen kan hebben voor de nationale veiligheid. Het onderzoek bevat een theoretisch en een empirisch gedeelte. De juridisch-theoretische methodologie bestond uit een studie van Nederlandse en buitenlandse regelgeving, rechtspraak en rechtsgeleerde literatuur. Het empirisch onderzoek vond plaats door middel van het houden van interviews.De volgende vitale sectoren komen aan bod: energie, ICT/Telecom, drinkwater en water, transport, chemie, de nucleaire sector, de financiële sector, de digitale overheid en defensie. Tevens is een analyse van in andere landen voorkomende regels die de nationale veiligheid tegen ongewenste buitenlandse investeringen pogen te beschermen, opgenomen. De onderzoekers bekeken achtereenvolgens het systeem in de Verenigde Staten van Amerika, in Duitsland, in Frankrijk, in het Verenigd Koninkrijk, in Noorwegen, in Zweden en in Zwitserland. INHOUD: 1. Inleiding 2. Kernbegrippen 3. Rechten van aandeelhouders 4. Analyse van vitale sectoren 5. Internationaal perspectief 6. Bevindingen, synthese en aanbevelingen 7. Summar