Biology subjects

Brauer-Nikonow, A.

Publications and source records attributed to Brauer-Nikonow, A..

3 recordsLinked to original sources

bioRxiv2024

Uncovering nitroxoline activity spectrum, mode of action and resistance across Gram-negative bacteria

Nitroxoline is a bacteriostatic quinoline antibiotic, considered a metal chelator inhibiting the activity of RNA-polymerase1. Its clinical indications are limited to uncomplicated urinary tract infections (UTIs), with a clinical susceptibility breakpoint only available for Escherichia coli2. By testing > 1,000 clinical isolates, here we demonstrate a much broader activity spectrum and species-specific bactericidal activity, including multidrug-resistant Gram-negative bacteria for which therapeutic options are limited due to resistance. By combining systematic genetic and proteomic approaches with direct measurement of intracellular metals, we dissect nitroxoline perturbation of metal homeostasis and unveil additional effects on bacterial physiology. We show that nitroxoline affects outer membrane integrity, synergizing with large-scaffold antibiotics and resensitizing colistin-resistant Enterobacteriaceae in vitro and in vivo. We further characterise resistance mechanisms across E. coli, Acinetobacter baumannii and Klebsiella pneumoniae, recapitulating known E. coli resistance determinants and uncovering novel and conserved mechanisms across species, demonstrating their common effect on nitroxoline efflux.

microbiology↗

bioRxiv2024

Unraveling interindividual differences and functional consequences of gut microbial metabolism of immunosuppressants

A major challenge in kidney transplantation (KT) is the large interpatient variability in the pharmacokinetics of immunosuppressive drugs. Here, we explored the role of the gut microbiome in interindividual variation in immunosuppressive drug metabolism. Analysis of 38 fecal communities, including 10 from KT recipients, and 45 bacterial species against 25 drugs, revealed significant interindividual and drug-specific differences in metabolism. Notably, 15 of 16 immunosuppressants tested were metabolized by at least one microbial community, and we found specific bacterial species, such as Bacteroides uniformis, to be potent metabolizers. We identified 18 different metabolites for 16 drugs, including two previously undescribed metabolites for sirolimus and everolimus. Our study reveals the functional impact of microbial metabolism on key immunosuppressants, including inactivation of tacrolimus, activation and potential increase in toxicity of mycophenolate mofetil (MMF), and shows that the microbial metabolite of methylprednisolone exhibits a 2.6-fold increase in epithelial permeability compared to the parent drug. Through a gain-of-function genetic screen we identified the B. uniformis enzyme BACUNI_RS05305 to be responsible for MMF activation. Using machine learning to model microbial community drug metabolism, abundance features of prevalent species predicted the biotransformation of some drugs well, while for others, a priori experimental information on bacterial genes and enzyme protein structures led to improved predictions. Our research highlights the potential of gut microbiome features to explain interindividual variability in immunosuppressive therapies and sets the stage for clinical trials to identify microbiome-encoded signatures predictive of drug metabolism in KT patients. One Sentence SummaryThis study reveals interindividual variability in gut microbial metabolism of immunosuppressive drugs mediated by specific bacterial species and enzymes.

microbiology↗

bioRxiv2023

Deep quantitative glycoproteomics reveals gut microbiome induced remodeling of the brain glycoproteome

HighlightsO_LIHigh throughput glycoproteomics method with multiplexed quantification C_LIO_LI25-fold improvement of the mouse brain glycoproteome coverage C_LIO_LIStructural features dictate level of glycosite micro-heterogeneity C_LIO_LIGut microbiome composition extensively impacts the brain glycoproteome C_LIO_LIModulation of glycosylation is site-specific C_LI Protein glycosylation is a highly diverse post-translational modification, modulating key cellular processes such as cell signaling, adhesion and cell-cell interactions. Its deregulation has been associated with various pathologies, including cancer and neurological diseases. Methods capable of quantifying glycosylation dynamics are essential to start unraveling the biological functions of protein glycosylation. Here we present Deep Quantitative Glycoprofiling (DQGlyco), a method that combines high-throughput sample preparation, high-sensitivity detection, and precise multiplexed quantification of protein glycosylation. We used DQGlyco to profile the mouse brain glycoproteome, in which we identify 158,972 and 15,056 unique N- and O-glycopeptides localized on 3,199 and 2,365 glycoproteins, respectively - this amounts to 25-fold more glycopeptides identified compared to previous studies. We observed extensive heterogeneity of glycoforms and determined their functional and structural preferences. The presence of a defined gut microbiota resulted in extensive remodeling of the brain glycoproteome when compared to that of germ-free animals, exemplifying how the gut microbiome may affect brain protein functions.

molecular biology↗