Biology subjects

Sorg, I.

Publications and source records attributed to Sorg, I..

4 recordsLinked to original sources

bioRxiv2026

Monitoring intracellular antibiotic concentrations in real-time using allosteric biosensors

Antibiotic treatment can fail due to insufficient drug availability at the site of infection or limited accumulation within bacterial pathogens. However, it is poorly understood how antibiotics penetrate infected tissues and complex bacterial aggregates, limiting insights into the mechanisms of treatment failure. Here, we present genetically-encoded allosteric biosensors for two antibiotic classes, trimethoprim and tetracycline, which enable real-time monitoring of antibiotic concentrations inside bacterial cells. The biosensors consist of circularly permuted EGFP linked to the sensory domains DHFR or TetR. To extend this approach to low oxygen environments, we engineered an oxygen-independent trimethoprim biosensor by fusing DHFR to a circularly permuted version of the fluorogenic protein FAST. Using these biosensors, we monitored the antibiotic exposure dynamics of intracellular Salmonella enterica during macrophage infection at the single-cell level, and antibiotic penetration into anaerobic regions of Vibrio cholerae biofilms, as well as antibiotic availability in microoxic conditions in a human bladder tissue model infected with uropathogenic Escherichia coli. These fluorescent biosensors have the potential to be broadly applied for determining antibiotic distributions at infection sites with high spatial and temporal resolution.

microbiology↗

bioRxiv2025

Perfusable 3D human urothelial model for real-time analysis of bacterial infection dynamics and therapeutic interventions

Urinary tract infections (UTIs) remain a major health burden, yet mechanistic studies are limited by the lack of experimental models that enable high spatiotemporal resolution tracking of infection dynamics, while recapitulating the stratified architecture of the bladder epithelium, urine tolerance and fluid dynamics. Here, we present a modular microphysiological platform integrating a fully stratified, urine-tolerant human urothelium cultured on standard transwell inserts within a custom-designed perfusion device compatible with live imaging. Urine flow enables real-time, high-resolution imaging of uropathogenic Escherichia coli (UPEC) infections under physiologically relevant conditions, including clearance of planktonic bacteria and nutrients replenishment, while retaining tissue-associated populations. This system revealed UPEC attachment via the type 1 fimbrial adhesin FimH and its inhibition by D-mannose treatment. Moreover, the platform captured L-form formation upon treatment with the frontline antibiotic fosfomycin and regrowth of walled bacteria following drug withdrawal. The platform further uncovered strain-specific lysis through bacteriophages in contrast to the activity of broad-spectrum antibiotics. In summary, this system constitutes a scalable platform with high predictive power for studying UTI pathogenesis and preclinical therapeutic testing.

bioengineering↗

bioRxiv2020

Structural basis for selective targeting of Rac subfamily GTPases by a bacterial effector protein

SummaryRas-homology (Rho) family GTPases are conserved molecular switches controlling fundamental cellular activities in eukaryotic cells. As such, they are targeted by numerous bacterial toxins and effector proteins, which have been intensively investigated regarding their biochemical activities and discrete target spectra; however, molecular mechanisms of target selectivity have remained elusive. Here, we report a bacterial effector protein that targets all four Rac subfamily members of Rho family GTPases, but none of the closely related Cdc42 or RhoA subfamilies. This exquisite target selectivity of the FIC domain AMP-transferase Bep1 from Bartonella rochalimae is based on electrostatic interactions with a subfamily-specific pair of residues in the nucleotide-binding motif and the Rho insert helix. Residue substitutions at the identified positions in Cdc42 facilitate modification by Bep1, while corresponding Cdc42-like substitutions in Rac1 greatly diminish modification. Our study establishes a structural paradigm for target selectivity towards Rac subfamily GTPases and provides a highly selective tool for their functional analysis.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biochemistry↗

bioRxiv2018

Genomic, Proteomic and Phenotypic Heterogeneity in HeLa Cells across Laboratories: Implications for Reproducibility of Research Results

The independent reproduction of research results is a cornerstone of experimental research, yet it is beset by numerous challenges, including the quality and veracity of reagents and materials. Much of life science research depends on life materials, including human tissue culture cells. In this study we aimed at determining the degree of variability in the molecular makeup and the ensuing phenotypic consequences in commonly used human tissue culture cells. We collected 14 stock HeLa aliquots from 13 different laboratories across the globe, cultured them in uniform conditions and profiled the genome-wide copy numbers, mRNAs, proteins and protein turnover rates via genomic techniques and SWATH mass spectrometry, respectively. We also phenotyped each cell line with respect to the ability of transfected Let7 mimics to modulate Salmonella infection.\n\nWe discovered significant heterogeneity between HeLa variants, especially between lines of the CCL2 and Kyoto variety. We also observed progressive divergence within a specific cell line over 50 successive passages. From the aggregate multi-omic datasets we quantified the response of the cells to genomic variability across the transcriptome and proteome. We discovered organelle-specific proteome remodeling and buffering of protein abundance by protein complex stoichiometry, mediated by the adaptation of protein turnover rates. By associating quantitative proteotype and phenotype measurements we identified protein patterns that explained the varying response of the different cell lines to Salmonella infection.\n\nAltogether the results indicate a striking degree of genomic variability, the rapid evolution of genomic variability in culture and its complex translation into distinctive expressed molecular and phenotypic patterns. The results have broad implications for the interpretation and reproducibility of research results obtained from HeLa cells and provide important basis for a general discussion of the value and requirements for communicating research results obtained from human tissue culture cells.

systems biology↗