Biology subjects

Grote, A.

Publications and source records attributed to Grote, A..

8 recordsLinked to original sources

bioRxiv2025

An Anaerobic Pathogen Rewires Host Metabolism to Fuel Oxidative Growth in the Inflamed Gut

To colonize their host and cause disease, enteric pathogens must deploy their virulence factors to establish distinct nutrient niches. How obligate anaerobic pathogens construct nutrient niches in the densely populated large intestine remains poorly understood. Enterotoxigenic Bacteroides fragilis (ETBF) is considered an obligate anaerobic bacterium and has been implicated in inflammation-associated diseases, including colitis and colorectal cancer. Here we show that ETBF uses its virulence factor, Bacteroides fragilis toxin, to reprogram colonic epithelial cell metabolism to colonize the inflamed gut. Bacteroides fragilis toxin activates colonic epithelial signaling and hijacks the host bile acid recycling pathway, inducing a metabolic shift in the epithelium from oxidative phosphorylation to glycolysis. This shift increases local concentrations of lactate and oxygen, nutrients that support an oxidative metabolism in ETBF. These findings reveal an unexpected strategy by which a pathogenic organism, previously considered to be an obligate anaerobic bacterium, generates and exploits an oxidative niche in the inflamed gut.

microbiology↗

bioRxiv2024

Proteomic profiling of IDH-wildtype Glioblastoma Tissue and Serum uncovers prognostic Subtypes and Marker Candidates

BackgroundIDH-wildtype glioblastoma (GBM) is the most prevalent primary brain cancer with a 5-year survival rate below 10%. Despite combined treatment through extensive resection and radiochemotherapy, nine out of ten patients develop recurrences. The lack of targeted treatment options and reliable diagnostic markers for recurrent tumors remain major challenges. Methods & AimsIn this study, we present the proteomic characterization of tissue and serum from 55 initial GBM tumors and five matching recurrences, which we investigated for proteomic tumor subtypes and proteomic signatures associated with recurrence. ResultsPrimary tumors revealed four distinct subgroups through hierarchical clustering: a neuronal cluster with elevated mature neuron markers, an innate immunity cluster with increased protease expression, a mixed cluster, and a stem-cell cluster. Neurodevelopmental and inflammatory processes were identified as key factors influencing clustering, with proteolytic activity increasing relative to the degree of inflammation. An analysis comprising proteins with lower coverage confirmed and expanded this pattern. Patients in the neuronal cluster exhibited significantly longer survival compared to those in the stem-cell cluster. In a patient-matched differential expression analysis, five recurrent tumors displayed significantly altered protein expression compared to their primary counterparts, emphasizing the proteomic plasticity of recurrent tumors. Investigation of serum proteomes before and after surgery, using a depletion-based protocol, revealed highly patient-specific and stable proteome compositions, despite a notable increase in inflammation markers post-surgery. However, the levels of circulating proteolytic products matched to the proteolytic activity within the tissue and one fragment of proteolysis activated receptor 2 (PAR2) consistently dropped in abundance after removal of inflamed tumors. ConclusionOverall, we describe a large proteomic GBM cohort. We identified distinct tumor subgroups, molecular patterns of recurrence, and matching proteomic patterns in the bloodstream, which may improve risk prediction for recurrent GBM.

cancer biology↗

bioRxiv2022

Persistent Salmonella infections in humans are associated with mutations in the BarA/SirA regulatory pathway

The bacterial pathogen Salmonella enterica is able to establish persistent infections, evading antibiotics and the host immune system and providing a reservoir for recrudescence and transmission to new hosts. Non-typhoidal serovars (NTS) of S. enterica can establish and maintain symptomatic and asymptomatic long term human infections that may predispose carriers to inflammatory bowel diseases and cancer. Defining the adaptations and host-pathogen interactions enabling these persistent infections is key to devising more effective strategies to combat and prevent persistent bacterial infections. Using comparative genomics of 639 Salmonella NTS isolates belonging to 49 serovars that were longitudinally obtained from 256 salmonelosis patients during different stages of infection, we identified numerous genetic variations accruing over time in strains isolated from the same patient. Many of these changes were found in the same gene across multiple patients and serovars. Among these variant loci, genes encoding global transcriptional regulators were found to be the most commonly mutated between early and late same-patient isolates. Genetic changes in the SirA/BarA two-component regulatory system were particularly frequent, with mutations identified in 24 independent patients. Comparative RNA-Seq analysis revealed that distinct mutations in sirA/barA that arose independently in late isolates of multiple patients lead to significantly diminished expression of virulence-associated genes encoded in the Salmonella Pathogenicity Islands (SPIs) 1 and 4, many of which are known to be critical for host cell invasion and the production of enteritis. Using the salmonellosis mouse model we showed that these mutations in sirA/barA genes confer attenuated virulence in-vivo. Taken together, these data suggest that selection of mutations in the SirA/BarA pathway facilitates persistent Salmonella infection in humans, possibly by attenuating Salmonella virulence and its ability to cause inflammation.

genomics↗

bioRxiv2021

Transcriptomics reveals how minocycline-colistin synergy overcomes antibiotic resistance in multidrug-resistant Klebsiella pneumoniae

Multidrug resistant gram-negative bacteria are a rapidly growing public health threat, and the development of novel antimicrobials has failed to keep pace with their emergence. Synergistic combinations of individually ineffective drugs present a potential solution, yet little is understood about the mechanisms of most such combinations. Here, we show that the combination of colistin (polymyxin E) and minocycline has a high rate of synergy against colistin-resistant and minocycline-intermediate or -resistant strains of Klebsiella pneumoniae. Furthermore, using RNA-Seq, we characterized the transcriptional profiles of these strains when treated with the drugs individually and in combination. We found a striking similarity between the transcriptional profiles of bacteria treated with the combination of colistin and minocycline at individually subinhibitory concentrations and those of the same isolates treated with minocycline alone. We observed a similar pattern with the combination of polymyxin B nonapeptide (a polymyxin B analogue that lacks intrinsic antimicrobial activity) and minocycline. We also found that genes involved in polymyxin resistance and peptidoglycan biosynthesis showed significant differential gene expression in the different treatment conditions, suggesting possible mechanisms for the antibacterial activity observed in the combination. These findings suggest that the synergistic activity of this combination against bacteria resistant to each drug alone involves sublethal outer membrane disruption by colistin, which permits increased intracellular accumulation of minocycline. IMPORTANCEFew treatment options exist for multidrug resistant gram-negative bacteria. Synergistic antimicrobial combinations (in which two individually inactive drugs regain activity when used in combination) can overcome resistance. In susceptible bacteria, minocycline acts inside the cell by preventing protein synthesis, while colistin disrupts the outer membrane. Even in bacteria resistant to both drugs, the combination of the two is active. To understand this activity, we studied Klebsiella pneumoniae isolates resistant to both drugs. We extracted messenger RNA during treatment with each drug alone and with the combination, then performed RNA sequencing to analyze gene expression levels. Bacteria treated with the combination had an expression profile similar to bacteria treated with minocycline alone. Our findings suggest that synergy results from low-level, subinhibitory membrane disruption by colistin, which permits sufficient accumulation of minocycline in the cell to overcome resistance. Understanding this pathway will facilitate further development of synergistic antimicrobial combination regimens.

microbiology↗

bioRxiv2021

Bacterial filamentation drives colony chirality

Chirality is ubiquitous in nature, with consequences at the cellular and tissue scales. As Escherichia coli colonies expand radially, an orthogonal component of growth creates a pinwheel-like pattern that can be revealed by fluorescent markers. To elucidate the mechanistic basis of this colony chirality, we investigated its link to left-handed, single-cell twisting during E. coli elongation. While chemical and genetic manipulation of cell width altered single-cell twisting handedness, colonies ceased to be chiral rather than switching handedness, and anaerobic growth altered colony chirality without affecting single-cell twisting. Chiral angle increased with increasing temperature even when growth rate decreased. Unifying these findings, we discovered that colony chirality was associated with the propensity for cell filamentation. Inhibition of cell division accentuated chirality under aerobic growth and generated chirality under anaerobic growth. Thus, regulation of cell division is intrinsically coupled to colony chirality, providing a mechanism for tuning macroscale spatial patterning.

microbiology↗

bioRxiv2021

StrainGE: A toolkit to track and characterize low-abundance strains in complex microbial communities

Human-associated microbial communities comprise not only complex mixtures of bacterial species, but also mixtures of conspecific strains, the implications of which are mostly unknown since strain level dynamics are underexplored due to the difficulties of studying them. We introduce the Strain Genome Explorer (StrainGE) toolkit, which deconvolves strain mixtures and characterizes component strains at the nucleotide level from short-read metagenomic sequencing with higher sensitivity and resolution than other tools. StrainGE is able to identify nearest known references and find variants for multiple conspecific strains within a sample at relative abundances below 0.1% in typical metagenomic datasets.

bioinformatics↗

bioRxiv2019

Prediction pipeline for discovery of regulatory motifs associated with Brugia malayi molting

Filarial nematodes can cause debilitating diseases in humans. They have complicated life cycles involving an insect vector and mammalian hosts, and they go through a number of developmental molts. While whole genome sequences of parasitic worms are now available, very little is known about transcription factor (TF) binding sites and their cognate transcription factors that play a role in regulating development. To address this gap, we developed a novel motif prediction pipeline, Emotif Alpha, that integrates ten different motif discovery algorithms, multiple statistical tests, and a comparative analysis of conserved elements between the filarial worms Brugia malayi and Onchocerca volvulus, and the free-living nematode Caenorhabditis elegans. We identified stage-specific TF binding motifs in B. malayi, with a particular focus on those potentially involved in the L3-L4 molt, a stage important for the establishment of infection in the mammalian host. Using an in vitro molting system, we tested and validated three of these motifs demonstrating the accuracy of the motif prediction pipeline.

bioinformatics↗

bioRxiv2019

Modeling the metabolic interplay between a parasitic worm and its bacterial endosymbiont allows the identification of novel drug targets

The filarial nematode Brugia malayi represents a leading cause of disability in the developing world, causing lymphatic filariasis in nearly 40 million people. Currently available drugs are not well-suited to mass drug administration efforts, so new treatments are urgently required. One potential vulnerability is the endosymbiotic bacteria Wolbachia--present in many filariae--which is vital to the worm.\n\nGenome scale metabolic networks have been used to study prokaryotes and protists and have proven valuable in identifying therapeutic targets, but only recently have been applied to eukaryotic organisms. Here, we present iDC625, the first compartmentalized metabolic model of a parasitic worm. We used this model to show how metabolic pathway usage allows the worm to adapt to different environments, and predict a set of 99 reactions essential to the survival of B. malayi. We validated three of those reactions with drug tests and demonstrated novel antifilarial properties for all three compounds.

systems biology↗