Biology subjects

Schirhagl, R.

Publications and source records attributed to Schirhagl, R..

3 recordsLinked to original sources

bioRxiv2025

Treating the untreatable: Reversing β-lactam resistance in MRSA by membrane-domain-dissolving antibiotics

Antimicrobial resistance is one of the most serious threats to global health with methicillin-resistant Staphylococcus aureus (MRSA) being the leading Gram-positive pathogen. Recently we discovered a new antimicrobial target for small antibiotics -- dissolution of functional domains in the bacterial membrane without pore formation. Here we apply this mechanism to reverse {beta}-lactam resistance in MRSA. We show that supplementation with a membrane-domain-dissolving antibiotic lowers the susceptibility of both a MRSA clinical isolate and the methicillin-susceptible S. aureus (MSSA) to multiple {beta}-lactams several folds. In particular, full reversal of resistance to oxacillin and penicillin in MRSA is achieved. We provide evidence on the nano-scale (atomic force microscopy), living bacteria (fluorescence microscopy), and bacterial cultures (microbiology assays) that the {beta}-lactam resistance reversal is linked to dissolution of membrane domains. A general nature of this principle is expected, and could be applied using various membrane-domain-dissolving antibiotics to reverse {beta}-lactam resistance in various bacteria. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=85 SRC="FIGDIR/small/684379v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@1608f24org.highwire.dtl.DTLVardef@55b460org.highwire.dtl.DTLVardef@b54337org.highwire.dtl.DTLVardef@4fef04_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOTOC Figure:C_FLOATNO Model of -lactam susceptibility renewal in MRSA based on data presented in this study. C_FIG

biophysics↗

bioRxiv2024

In Silico Vaccine Design: Targeting Highly Epitopic Regions of Clostridium perfringens Type D Epsilon Toxin and Clostridium novyi Type B Alpha Toxin for Optimal Immunogenicity

Livestock infections caused by highly toxic bacteria pose significant challenges in veterinary medicine, often requiring complex and elusive treatment regimens. Developing effective vaccines tailored to combat these specific pathogens remains a pressing need within the field. Among the most formidable culprits are Clostridium perfringens type D and Clostridium novyi type B, notorious for their extreme toxicity and the difficulty in culturing them for vaccine production. In response to this challenge, our study endeavors to engineer a vaccine candidate capable of concurrently neutralizing the virulence of both bacterial strains. Leveraging computational techniques, we meticulously identified highly epitopic regions within C. perfringens Epsilon Toxin (ETX) and C. novyi Alpha Toxin (ATX), crucial targets for effective immunization. Through innovative fusion gene design, we integrated these epitopic regions alongside the PADRE-peptide sequence, serving as a universal adjuvant to bolster immune response. The culmination of our efforts materialized in the creation of Recombinant Fusion Protein D (rFPD), a novel vaccine construct poised to elicit robust and specific immune defenses against both bacterial species. By harnessing the power of in silico design and molecular engineering, our study heralds a promising stride towards mitigating the deleterious impact of livestock infections caused by these formidable pathogens.

bioinformatics↗

bioRxiv2023

Evolution of intracellular free radical load in colon adenocarcinoma cells over the course of butyrate-induced redifferentiation

Fluorescent nanodiamonds have exceptional optical properties and are highly biocompatible, which allows to use them as labels for long-term tracking of the cells. The research fields that make use of this application of nanodiamonds include stem cell biology and cancer biology, where quiescent and differentiating cells can be traced in vitro and in vivo. However, these studies focus on using nanodiamonds as simple labels, whereas they can serve as highly sensitive intracellular sensors for free radical species. In this study, we aimed to bring the two approaches together and to assess the free radical production in the cells over the course of their differentiation. We report on the successful enterocytic differentiation of HT-29 colon adenocarcinoma cells, pre-loaded with fluorescent nanodiamonds. The cells were cultured in butyrate-free or butyrate-supplemented medium for 13 days. Butyrate-treated cells developed the morphological and molecular traits, characteristic for normal enterocytes. Fluorescent nanodiamonds did not have a negative effect on the process of differentiation. Moreover, the particles could be found in the cytoplasm of both undifferentiated and re-differentiated cells even after 13 days of culture. The internalized nanodiamonds were used to assess the free radical load in the undifferentiated and re-differentiated HT-29 cells at different stages of the experiment. Consistently with previous findings, re-differentiated HT-29 cells showed higher free radical load than undifferentiated ones.

cell biology↗