The contribution of achiral residues in the laspartomycin family of calcium-dependent lipopeptide antibiotics

The growing threat of antibacterial resistance is a global concern. The so-called calcium-dependent lipopeptide antibiotics (CDAs) have emerged as a promising source of new antibiotic agents that are rich in structural and mechanistic diversity. Over forty unique CDAs have been identified to date and share a number of common features. Recent efforts in our group have provided new mechanistic and structural insights into the laspartomycin family of CDAs. We here describe investigations aimed at probing the role of the three glycine residues found in the laspartomycin peptide macrocycle. In doing so laspartomycin analogues containing the achiral 2-aminoisobutyric acid (AIB) as well as L- or D-alanine in place of glycine were prepared and their antibacterial activities evaluated.Microbial Biotechnolog

Thrombin-derived peptides potentiate the activity of Gram-positive-specific antibiotics against Gram-negative bacteria

Microbial Biotechnolog

Mechanistic insights into the C₅₅-P targeting lipopeptide antibiotics revealed by structure-activity studies and high-resolution crystal structures

AbstractThe continued rise of antibiotic resistance is a global concern that threatens to undermine many aspects of modern medical practice. Key to addressing this threat is the discovery and development of new antibiotics that operate by unexploited modes of action. The so-called calcium-dependent lipopeptide antibiotics (CDAs) are an important emerging class of natural products that provides a source of new antibiotic agents rich in structural and mechanistic diversity. Notable in this regard is the subset of CDAs comprising the laspartomycins and amphomycins/friulimicins that specifically target the bacterial cell wall precursor undecaprenyl phosphate (C55-P). In this study we describe the design and synthesis of new C55-P-targeting CDAs with structural features drawn from both the laspartomycin and amphomycin/friulimicin classes. Assessment of these lipopeptides revealed previously unknown and surprisingly subtle structural features that are required for antibacterial activity. High-resolution crystal structures further indicate that the amphomycin/friulimicin-like lipopeptides adopt a unique crystal packing that governs their interaction with C55-P and provides an explanation for their antibacterial effect. In addition, live-cell microscopy studies provide further insights into the biological activity of the C55-P targeting CDAs highlighting their unique mechanism of action relative to the clinically used CDA daptomycin.Microbial Biotechnolog

Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper

Oxide‐derived copper (OD‐Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at −0.3 V (vs. RHE). By using static headspace‐gas chromatography for liquid phase analysis, we identify acetaldehyde as a minor product and key intermediate in the electroreduction of CO to ethanol on OD‐Cu electrodes. Acetaldehyde is produced with a Faradaic efficiency of ≈5 % at −0.33 V (vs. RHE). We show that acetaldehyde forms at low steady‐state concentrations, and that free acetaldehyde is difficult to detect in alkaline solutions using NMR spectroscopy, requiring alternative methods for detection and quantification. Our results represent an important step towards understanding the CO reduction mechanism on OD‐Cu electrodes

Mechanistic insights into the C₅₅-P targeting lipopeptide antibiotics revealed by structure-activity studies and high-resolution crystal structures

The continued rise of antibiotic resistance is a global concern that threatens to undermine many aspects of modern medical practice. Key to addressing this threat is the discovery and development of new antibiotics that operate by unexploited modes of action. The so-called calcium-dependent lipopeptide antibiotics (CDAs) are an important emerging class of natural products that provides a source of new antibiotic agents rich in structural and mechanistic diversity. Notable in this regard is the subset of CDAs comprising the laspartomycins and amphomycins/friulimicins that specifically target the bacterial cell wall precursor undecaprenyl phosphate (C(55)-P). In this study we describe the design and synthesis of new C(55)-P-targeting CDAs with structural features drawn from both the laspartomycin and amphomycin/friulimicin classes. Assessment of these lipopeptides revealed previously unknown and surprisingly subtle structural features that are required for antibacterial activity. High-resolution crystal structures further indicate that the amphomycin/friulimicin-like lipopeptides adopt a unique crystal packing that governs their interaction with C(55)-P and provides an explanation for their antibacterial effect. In addition, live-cell microscopy studies provide further insights into the biological activity of the C(55)-P targeting CDAs highlighting their unique mechanism of action relative to the clinically used CDA daptomycin

Live-cell imaging of sterculic acid - a naturally occurring 1,2-cyclopropene fatty acid - by bioorthogonal reaction with turn-on tetrazine-fluorophore conjugates

In the field of lipid research, bioorthogonal chemistry has made the study of lipid uptake and processing in living systems possible, whilst minimising biological properties arising from detectable pendant groups. To allow the study of unsaturated free fatty acids in live cells, we here report the use of sterculic acid, a 1,2-cyclopropene-containing oleic acid analogue, as a bioorthogonal probe. We show that this lipid can be readily taken up by dendritic cells without toxic side effects, and that it can subsequently be visualised using an inverse electron-demand Diels-Alder reaction with quenched tetrazine-fluorophore conjugates. In addition, the lipid can be used to identify changes in protein oleoylation after immune cell activation. Finally, this reaction can be integrated into a multiplexed bioorthogonal reaction workflow by combining it with two sequential copper-catalysed Huisgen ligation reactions. This allows for the study of multiple biomolecules in the cell simultaneously by multimodal confocal imaging.NWOERC-CoG 865175Molecular PhysiologyBio-organic Synthesi

GRAPPA-OMERACT consensus-based recommendations and research agenda for use of composite measures and treatment targets in PsA

BACKGROUND: Many composite disease activity measures and targets have been developed for psoriatic arthritis (PsA). This GRAPPA-OMERACT work stream aimed to further the development of consensus among physicians and patients.METHODS: Prior to the meeting, physicians and patients were surveyed on outcome measures. A consensus meeting (26 rheumatologists, dermatologists, and patient representatives) reviewed evidence on composite measures and potential treatment targets, plus survey results. After discussions, participants voted on proposals for use and consensus was established in a second survey.RESULTS: Survey results from 128 HCPS and 139 patients were analysed alongside a SLR summarising evidence. A weighted vote was cast for composite measures (for RCTs, most popular measures were PASDAS [40 votes] and GRACE [28 votes]; for clinical practice, most popular were 3-VAS [45 votes], DAPSA [26 votes]). After discussion there was no consensus on a composite measure. The group agreed that several composite measures could be used. Future studies should allow further validation and comparison. The group unanimously agreed that remission should be the ideal target with minimal/low disease activity a feasible alternative. The target should include assessment of musculoskeletal disease, skin and health related quality of life. The group recommended a target of treatment as VLDA, or MDA.CONCLUSIONS: Consensus was not reached on a continuous measure of disease activity. In the interim the group recommends several composites. Consensus was reached on a treatment target of VLDA/MDA. An extensive research agenda was composed and recommends that data on all PsA clinical domains be collected in ongoing studies. This article is protected by copyright. All rights reserved.</p

Apathy in rapid eye movement sleep behaviour disorder is common and under-recognised

Background Apathy is an important neuropsychiatric feature of Parkinson’s disease (PD), which often emerges before the onset of motor symptoms. Patients with rapid eye movement sleep behaviour disorder (RBD) have a high probability of developing Parkinson’s disease in future. Neuropsychiatric problems are common in RBD, but apathy has not previously been detailed in this key prodromal population. Methods 88 patients with polysomnographically proven RBD, 65 patients with PD and 33 controls were assessed for apathy using the Lille Apathy Rating Scale (LARS). Cognition and depression were also quantified. The sensitivity of the Unified Parkinson’s Disease Rating Scale screening questions for apathy and depression was calculated. Results 46% of Patients with RBD were apathetic, compared with 31% of Parkinson’s patients in our sample. Most RBD patients with depression were apathetic but more than half of apathetic patients were not depressed. The sensitivity of the single UPDRS screening question was only 33% for mild apathy and 50% for severe apathy. Conclusions Apathy is common in RBD and is underestimated by a single self-report question. Recognition of apathy as a distinct neuropsychiatric feature in RBD could aid targeted treatment interventions and might contribute to understanding of prodromal Parkinson’s disease.</p