Biology subjects

Goettig, S.

Publications and source records attributed to Goettig, S..

6 recordsLinked to original sources

bioRxiv2026

Cell-envelope conduits enable transfer of megabase-sized double-stranded DNA between cells of the nosocomial pathogen Acinetobacter baumannii

Horizontal gene transfer in Acinetobacter baumannii has been attributed to conjugative pili, transduction, and natural transformation. Here, we describe a previously unrecognized type of chromosomal DNA exchange mediated by cell-envelope conduits that establish direct cytoplasmic continuity between neighboring A. baumannii cells. Cryo-electron tomography reveals that these conduits, which were found in multiple clinical isolates, comprise an outer membrane, a peptidoglycan layer, and an inner membrane. The ~65 nm-thick conduits contain two ~2 nm-thick filaments, which super-resolution microscopy identifies as DNA. Interstrain horizontal gene transfer assays coupled with whole-genome sequencing demonstrate the transfer and homologous recombination of chromosomal segments up to 1.1 Mbp, corresponding to as much as 27% of the A. baumannii genome. Together, these findings provide direct structural and functional evidence for a conduit-mediated large-scale chromosomal DNA exchange, thus expanding the known repertoire of horizontal gene transfer strategies that may contribute to the remarkable genomic plasticity of A. baumannii.

microbiology↗

bioRxiv2026

Machine learning-guided discovery of a conserved plasmid proteomic signature enables MALDI-TOF MS detection of pOXA-48-carrying Enterobacterales

OXA-48 carbapenemases are among the most widespread and important resistance mechanisms in Enterobacterales. Yet detecting carbapenemases by conventional workflows necessitates additional testing, thus delaying optimization of therapy and implementation of infection control measures. Here, we present a machine learning approach that identifies the conserved pOXA-48 plasmid directly from routine MALDI-TOF spectra acquired for species identification. The model detects pOXA-48 carriers with an AUROC of 0.96-0.98 across two independent hospital cohorts and instrument platforms, indicating near-perfect discrimination. Using bottom-up proteomics, plasmid conjugation, and plasmid curing, we link the discriminative MALDI-TOF spectral features to proteins encoded on pOXA-48, with DUF1496 domain-containing protein producing the most discriminative spectral feature. Our approach reframes the resistance prediction task from inferring a resistance phenotype to detecting a conserved plasmid through its expressed proteomic signature and has the potential to enable rapid MALDI-TOF MS-based diagnostics for a wide range of plasmid-based resistance determinants.

microbiology↗

bioRxiv2025

OXA-1207, a new OXA-48-type carbapenem-hydrolysing class D beta lactamase from Escherichia coli

1.We present the characterisation of OXA-1207, a novel, plasmid-encoded OXA-48-like carbapenemase identified in two unrelated Escherichia coli (sequence type (ST) ST405 and ST4405) isolates from hospital patients in Germany. OXA-1207 is closely related to OXA-181, differing by two amino acid substitutions (214G and 244W). The blaOXA-1207 gene was located on a self-transmissible IncFIC plasmids (pOXA-1207) featuring a conserved backbone and the novel {Delta}Tn6361 transposon structure, which derived from IncX3 plasmids carrying blaOXA-181. Notably, pOXA-1207 exhibited an exceptionally high conjugation frequency (mean 1.2 x 10-1) to E. coli, surpassing the typical rates reported for widely distributed OXA-48 plasmids. Analysis of public genomic datasets identified 40 E. coli isolates carrying blaOXA-1207, belonging to diverse high-risk clonal lineages (ST167, ST405 and ST410). The isolates originated from multiple continents, indicating global dissemination. These findings highlight OXA-1207 as an emerging and concerning resistance determinant with enhanced transmissibility and emphasise the need for continued molecular surveillance of OXA-48-like carbapenemases.

microbiology↗

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↗

bioRxiv2022

CipA mediates complement resistance of Acinetobacter baumannii by formation of a Factor I-dependent quadripartite assemblage

Multidrug-resistant Acinetobacter baumannii is known to be one of the leading pathogens that cause severe nosocomial infections. To overcome eradication by the innate immune system during infection, A. baumannii developed a number of immune evasion strategies. Previously, we identified CipA as a plasminogen-binding and complement-inhibitory protein. Here we show that CipA strongly inhibits all three complement activation pathways and interacts with key complement components C3, C3b, C4b, C5, Factor B, Factor D, and in particular Factor I. CipA also targets function of the C5 convertase as cleavage of C5 was impaired. Systematic screening of CipA variants identified two separate binding sites for C3b and a Factor I-interacting domain located at the C-terminus. Structure predictions using AlphaFold2 and binding analyses employing CipA variants lacking Factor I-binding capability confirmed that the orientation of the C-terminal domain is essential for the interaction with Factor I. Hence, our analyses point to a novel, Factor I-dependent mechanisms of complement inactivation mediated by CipA of A. baumannii. Recrutiment of Factor I by CipA initiates the assembly of a quadripartite complex following binding of either Factor H or C4b-binding protein to degrade C3b and C4b, respectively. Loss of Factor I binding in a CipA-deficient strain, or a strain producing a CipA variant lacking Factor I-binding capability, correlated with a higher susceptibility to human serum, indicating that recruitment of Factor I enables A. baumannii to resist complement-mediated killing. Significance StatementThe Gram-negative bacterium Acinetobacter baumannii causes severe nosocomial infections and has developed various immune evasion strategies to overcome complement. The mechanisms how Acinetobacter baumannii successfully circumvents complement-mediated bacteriolysis are still poorly understood. Here, we show that the plasminogen-binding and complement inhibitory protein CipA terminates all three complement activation pathways. We describe a novel mechanism by which CipA cleaves the key complement components C3b and C4b in the presence of Factor H and C4b-binding protein by formation of a novel Factor I-dependent quadripartite complex. CipA, which has recently been successfully used for vaccination approaches, might represent an attractive target for the development of novel therapeutic interventions to block disorders with excessive hyperinflammatory complement activation.

microbiology↗

bioRxiv2018

Multi-omics approach identifies novel pathogen-derived prognostic biomarkers in patients with Pseudomonas aeruginosa bloodstream infection

Pseudomonas aeruginosa is a human pathogen that causes health-care associated blood stream infections (BSI). Although P. aeruginosa BSI are associated with high mortality rates, the clinical relevance of pathogen-derived prognostic biomarker to identify patients at risk for unfavorable outcome remains largely unexplored. We found novel pathogen-derived prognostic biomarker candidates by applying a multi-omics approach on a multicenter sepsis patient cohort. Multi-level Cox regression was used to investigate the relation between patient characteristics and pathogen features (2298 accessory genes, 1078 core protein levels, 107 parsimony-informative variations in reported virulence factors) with 30-day mortality. Our analysis revealed that presence of the helP gene encoding a putative DEAD-box helicase was independently associated with a fatal outcome (hazard ratio 2.01, p = 0.05). helP is located within a region related to the pathogenicity island PAPI-1 in close proximity to a pil gene cluster, which has been associated with horizontal gene transfer. Besides helP, elevated protein levels of the bacterial flagellum protein FliL (hazard ratio 3.44, p < 0.001) and of a bacterioferritin-like protein (hazard ratio 1.74, p = 0.003) increased the risk of death, while high protein levels of a putative aminotransferase were associated with an improved outcome (hazard ratio 0.12, p < 0.001). The prognostic potential of biomarker candidates and clinical factors was confirmed with different machine learning approaches using training and hold-out datasets. The helP genotype appeared the most attractive biomarker for clinical risk stratification due to its relevant predictive power and ease of detection.

microbiology↗