Biology subjects

Elhenawy, W.

Publications and source records attributed to Elhenawy, W..

4 recordsLinked to original sources

bioRxiv2026

Discovery of inhibitors of the Pseudomonas aeruginosa NADH:ubiquinone oxidoreductase (NQR) that hinder virulence factors

The growing threat of antimicrobial resistance has created an urgent need to identify novel therapeutic targets in bacteria. The NADH:ubiquinone oxidoreductase (NQR) is a potential target in a number of bacteria that transfers electrons from NADH to ubiquinone while pumping ions from the cytoplasm to the periplasm. In most species, this complex pumps sodium ions, whereas in Pseudomonas aeruginosa it pumps protons, thereby functioning as a member of the electron transport chain. Using a strain of PAO1 with the NQR knocked out, we demonstrate that the NQR complex plays a crucial role in the motility and biofilm development virulence factors in P. aeruginosa. We develop and execute a high-throughput inhibitor screen to identify and confirm compounds that inhibit NADH oxidation by this complex. Using single-particle cryogenic electron microscopy (cryoEM), we determine high-resolution structures of the NQR complex, both inhibitor-free and bound to one of the confirmed hits from our screen, demonstrating that it binds to the ubiquinone binding site. These structures provide insight into conformational dynamics controlled by binding at the ubiquinone site, with potential implications for the coupling between electron transfer and proton pumping in this complex. Biofilm development and motility assays with selected compounds from the screen show that they affect these virulence factors similarly to the NQR knockout.

biochemistry↗

bioRxiv2025

Mechanistic insight into the regulation of virulence factor type 1 pili in pathogenic E. coli by rhomboid protease GlpG

With the rise in antimicrobial resistance, understanding the virulence factors utilized by pathogenic E. coli is essential for the development of alternative therapeutics. While previous work has shown that disruption of the E. coli rhomboid protease gene glpG leads to defects in bacterial colonization, here we provide mechanistic insight into the loss of fitness. We show GlpG is essential for the assembly of type 1 pili, a virulence factor required for the colonization of eukaryotic cells. Since pili are critical for biofilm formation and bacterial persistence, the absence of GlpG proteolytic activity reduces the production of biofilm. Working towards new potential antimicrobial targets for treating infections, we show that biofilm formation is hampered by GlpG inhibition. Our data demonstrates that GlpG plays a key role in protein quality control of type 1 pili and alters the paradigm for GlpG proteolysis, previously implicated in the cleavage of only membrane embedded substrates.

biochemistry↗

bioRxiv2024

Discovery of broad-spectrum bacterial polyamine detoxification inhibitors as potential antivirulence agents and antibiotic adjuvants

The alarming rise in antimicrobial resistance reinforces an urgent need for new antimicrobial strategies. Host- or bacteria-derived chemicals, such as polyamines, present at infection sites often influence microbial virulence and antibiotic response. Polyamines are cationic small molecules overproduced by the host during infection, modulating immune responses. Polyamine detoxification by several pathogens correlates with increased virulence. We sought to uncover inhibitors of polyamine detoxification through a high-throughput whole-cell screen against the community-acquired methicillin-resistant Staphylococcus aureus (MRSA) USA300, identifying the polyamine analog OES2-0017 and the catechol derivative isoproterenol (OES1-1087), which synergized with polyamines in the low-micromolar range. Chemical genomics and enzymatic assays combined with computational studies revealed that both compounds prevented polyamine detoxification by spermine/spermidine acetyltransferase SSAT (SpeG) and another previously uncharacterized S. aureus SSAT (denoted PaiASa herein). OES2-0017 directly inhibited the enzymes, whereas OES1-1087 reduced intracellular levels of acetyl-CoA required for SSAT activity. OES2-0017 perturbed the bacterial membrane at higher concentrations, likely causing the observed growth-inhibitory effects, whereas OES1-1087 increased membrane fluidity, likely increasing susceptibility to spermine-mediated membrane perturbation. The inhibitors showed broad-spectrum activity against various Gram-positive and Gram-negative bacteria, as well as Candida albicans. OES2-0017 abolished the spermine-mediated protection of MRSA USA300 from antibiotics, including vancomycin, phenocopying the {Delta}speG mutant and suggesting its potential utility as an antibiotic adjuvant. OES2-0017 eradicated SpeG-expressing Salmonella Typhimurium inside murine macrophages, whereas OES1-1087 reduced the S. Typhimurium burden in the liver and spleen in a murine gastrointestinal infection model, demonstrating their potential as antivirulence agents. Neither inhibitor exhibited cytotoxic activity against eukaryotic cells at their respective antimicrobial ranges. Small-scale structure-activity relationship experimental and computational analyses identified OES2-0017 analogs with improved specificity for the bacterial enzyme compared to the human SAT1 and no toxicity. This study provides novel antimicrobial compounds with broad-spectrum activity and a novel mode of action for multidrug-resistant priority pathogens.

microbiology↗

bioRxiv2018

A macrophage-based screen identifies antibacterial compounds selective for intracellular Salmonella Typhimurium

Salmonella Typhimurium (S. Tm) evades the innate immune response by residing within host phagocytes. To identify inhibitors of intracellular S. Tm growth, we performed parallel chemical screens against S. Tm growing in macrophage-mimicking media and within macrophages. These screens identified novel antibacterials, and revealed that antibiotics with limited Gram-negative coverage are active against intracellular S. Tm. Screening of a S. Tm deletion library in the presence of one compound, metergoline, revealed that outer membrane perturbation enhanced activity in vitro. Combined with our observation of atypical cell surface characteristics of intracellular S. Tm, our work indicates that the bacterial outer membrane is permeabilized within macrophages. We show that metergoline targets the bacterial cytoplasmic membrane, and prolongs animal survival during a systemic S. Tm infection. This work highlights the predictive nature of intracellular screens for in vivo efficacy, and uncovers new aspects of bacterial physiology of intracellular S. Tm.

microbiology↗