Biology subjects

Ramsbeck, D.

Publications and source records attributed to Ramsbeck, D..

3 recordsLinked to original sources

bioRxiv2025

Effect of a bacterial Glutaminyl Cyclase inhibitor on multi-species-biofilms

Modifying bacterial virulence could be an interesting alternative to antibiotics. The study aimed to examine the effects of an inhibitor targeting bacterial glutaminyl cyclase (which is selectively present in Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), and Prevotella intermedia (Pi)) on various multispecies biofilms. Two multi-species biofilms--one containing four species (including Tf) and another with 12 species (including Tf, Pg, and Pi)--were cultured in the presence of 31.25-500 {micro}M of a [4,5-c]pyridine-based inhibitor. After 24 hours, bacterial counts, biofilm mass, metabolic activity, and, when Pg was included, Arg-gingipain activity were measured. Additionally, the biofilms were exposed to monocytic cells; here, the release of interleukin (IL)-1{beta} and IL-10 was analyzed. The data were analyzed using a one-way analysis of variance (ANOVA) with a post-hoc comparison performed using the Bonferroni correction. In all biofilms, total bacterial counts and those of Pg and Tf remained unaffected by the inhibitor. In the 12-species biofilm, both mass" and total metabolic activity decreased at high inhibitor concentrations (500 {micro}M to 75.2{+/-}6.5% and 87.2{+/-}5.8%, respectively; each p<0.001). The arginine-specific amidolytic activities of Rgp declined dose-dependently, down to 60.4{+/-}10.2% (p<0.001) at 500 {micro}M of the inhibitor. Consequently, Pg colonies lost pigmentation as inhibitor concentrations increased. The inhibitor also reduced IL-1{beta} release from monocytic cells stimulated by the 12-species biofilm. The studied [4,5-c]pyridine-based inhibitor is able to modify virulence of a multispecies biofilm. It might have the potential to be a promising approach in periodontal prevention and therapy.

microbiology↗

bioRxiv2025

Novel small molecule targeting PgQC reduces Porphyromonas gingivalis virulence

Periodontitis, a chronic inflammatory disease affecting the periodontium, is primarily driven by dysbiotic of the oral microbiome with Porphyromonas gingivalis as a keystone pathogen. Current therapeutic approaches rely on mechanical debridement and antimicrobials, which face limitations including antibiotic resistance and microbiome disruption. Pathoblockers represent a novel therapeutic strategy that selectively targets virulence factors without bactericidal effects, potentially reducing resistance development while preserving beneficial microbiota. Here, we describe the characterization of S-0636, a novel reversible inhibitor of zinc-dependent glutaminyl cyclase (PgQC), as a compound to selectively suppress growth of P. gingivalis. The compounds effects was assessed through enzymatic assays, bacterial growth studies, virulence factor activity measurements (gingipain activity, hemagglutination, keratinocyte invasion), selectivity testing against commensal oral bacteria, resistance development analysis over 50 passages, and cytotoxicity evaluation in human cell lines. S-0636 demonstrated potent PgQC inhibition with a Ki value of 0.014 M and has successfully reduced the intracellular PgQC activity by 50% at 8 M and had no bactericidal effects. Treatment of P. gingivalis with S-0636 significantly decreased gingipain activity, impaired hemagglutination capacity, and reduced keratinocyte invasion by 76% at 62.5 M. The compound showed high selectivity, with no growth inhibition of ten tested oral commensal species at concentrations up to 0.25 mM. Importantly, no resistance development was observed after 50 bacterial passages, and cytotoxicity remained minimal in human cell lines with >80% viability at 0.5 mM. In previous studies, PgQC was suggested as an enzyme responsible for pGlu-modification and stabilization of bacterial virulence factors. The current study now validates PgQC as an attractive target for pathoblocker development, demonstrating that S-0636 effectively attenuates P. gingivalis pathogenicity through selective virulence factor inhibition while preserving bacterial viability and oral microbiome integrity. The absence of resistance development and low cytotoxicity profile support the potential clinical translation of this approach for periodontal disease management, representing a promising alternative to conventional antimicrobial therapies.

microbiology↗

bioRxiv2022

Helical ultrastructure of the oncogenic metalloprotease meprin α in complex with a small molecule hydroxamate inhibitor

The zinc-dependent metalloprotease meprin is predominantly expressed in the brush border membrane of proximal tubules in the kidney and enterocytes in the small intestine and colon. In normal tissue homeostasis meprin performs key roles in inflammation, immunity, and extracellular matrix remodelling. The latter activity is furthermore important for driving aggressive metastasis in the context of certain cancers such as colorectal carcinoma. Accordingly, meprin is the target of drug discovery programs. In contrast to meprin {beta}, meprin is secreted into the extracellular space, whereupon it oligomerises to form giant assemblies and is the largest extracellular protease identified to date (~6 MDa). Here, using cryo-electron microscopy, we determine the high-resolution structure of the zymogen and mature form of meprin , as well as the structure of the active form in complex with a prototype small molecule inhibitor and human fetuin-B. Our data reveal that meprin forms a giant, flexible, left-handed helical assembly of roughly 22 nm in diameter. We find that oligomerisation improves proteolytic and thermal stability but does not impact substrate specificity or enzymatic activity. Furthermore, structural comparison with meprin {beta} reveal unique features of the active site of meprin , and helical assembly more broadly.

biochemistry↗