scholarly journals Structural insights into a novel family of integral membrane siderophore reductases

2021 ◽  
Vol 118 (34) ◽  
pp. e2101952118
Author(s):  
Inokentijs Josts ◽  
Katharina Veith ◽  
Vincent Normant ◽  
Isabelle J. Schalk ◽  
Henning Tidow
Keyword(s):  
Iron Uptake ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Gram Negative ◽  
Inner Membrane Protein ◽  
Uptake Studies ◽  
Structural Insights

Gram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from Pseudomonas aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a fold with two tightly bound heme molecules. In combination with in vitro reduction assays and in vivo iron uptake studies, these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.

scholarly journals Structural insights into a novel family of integral membrane siderophore reductases

2021 ◽  
Author(s):  
Inokentijs Josts ◽  
Katharina Veith ◽  
Vincent Normant ◽  
Isabelle J. Schalk ◽  
Henning Tidow
Keyword(s):  
Crystal Structure ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Inner Membrane ◽  
Gram Negative ◽  
Functional Studies ◽  
Inner Membrane Protein ◽  
Structural Insights

AbstractGram-negative bacteria take up the essential ion Fe3+ as ferric-siderophore complexes through their outer membrane using TonB-dependent transporters. However, the subsequent route through the inner membrane differs across many bacterial species and siderophore chemistries and is not understood in detail. Here, we report the crystal structure of the inner membrane protein FoxB (from P. aeruginosa) that is involved in Fe-siderophore uptake. The structure revealed a novel fold with two tightly-bound heme molecules. In combination with functional studies these results establish FoxB as an inner membrane reductase involved in the release of iron from ferrioxamine during Fe-siderophore uptake.

scholarly journals Defining the function of OmpA in the Rcs stress response

2020 ◽  
Author(s):  
Juliette Létoquart ◽  
Kilian Dekoninck ◽  
Cédric Laguri ◽  
Pascal Demange ◽  
Robin Bevernaegie ◽  
...  
Keyword(s):  
Stress Response ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Bacterial Surface ◽  
Periplasmic Domain ◽  
Inner Membrane Protein

AbstractOmpA, a protein commonly found in the outer membrane of Gram-negative bacteria, has served as a paradigm for the study of β-barrel proteins for several decades. In Escherichia coli, OmpA was previously reported to form complexes with RcsF, a surface-exposed lipoprotein that triggers the Rcs stress response when damage occurs in the outer membrane and the peptidoglycan. How OmpA interacts with RcsF and whether this interaction allows RcsF to reach the surface has remained unclear. Here, we integrated in vivo and in vitro approaches to establish that RcsF interacts with the C-terminal, periplasmic domain of OmpA, not with the N-terminal β-barrel, thus implying that RcsF does not reach the bacterial surface via OmpA. Our results reveal a novel function for OmpA in the cell envelope: OmpA competes with the inner membrane protein IgaA, the downstream Rcs component, for RcsF binding across the periplasm, thereby regulating the Rcs response.

scholarly journals Defining the function of OmpA in the Rcs stress response

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Kilian Dekoninck ◽  
Juliette Létoquart ◽  
Cédric Laguri ◽  
Pascal Demange ◽  
Robin Bevernaegie ◽  
...  
Keyword(s):  
Stress Response ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Bacterial Surface ◽  
Periplasmic Domain ◽  
Inner Membrane Protein

OmpA, a protein commonly found in the outer membrane of Gram-negative bacteria, has served as a paradigm for the study of β-barrel proteins for several decades. In Escherichia coli, OmpA was previously reported to form complexes with RcsF, a surface-exposed lipoprotein that triggers the Rcs stress response when damage occurs in the outer membrane and the peptidoglycan. How OmpA interacts with RcsF and whether this interaction allows RcsF to reach the surface has remained unclear. Here, we integrated in vivo and in vitro approaches to establish that RcsF interacts with the C-terminal, periplasmic domain of OmpA, not with the N-terminal β-barrel, thus implying that RcsF does not reach the bacterial surface via OmpA. Our results suggest a novel function for OmpA in the cell envelope: OmpA competes with the inner membrane protein IgaA, the downstream Rcs component, for RcsF binding across the periplasm, thereby regulating the Rcs response.

scholarly journals In Vitro and In Vivo Antibacterial Activities of DW-224a, a New Fluoronaphthyridone

2006 ◽  
Vol 50 (6) ◽  
pp. 2261-2264 ◽  
Author(s):  
Hee-Soo Park ◽  
Hyun-Joo Kim ◽  
Min-Jung Seol ◽  
Dong-Rack Choi ◽  
Eung-Chil Choi ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
The Other ◽  
Vitro Activity ◽  
Gram Negative Bacteria ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

ABSTRACT DW-224a showed the most potent in vitro activity among the quinolone compounds tested against clinical isolates of gram-positive bacteria. Against gram-negative bacteria, DW-224a was slightly less active than the other fluoroquinolones. The in vivo activities of DW-224a against gram-positive bacteria were more potent than those of other quinolones.

Cefotaxime and amikacin: results of in vitro and in vivo studies against Gram-negative bacteria and Staphylococcus aureus

1980 ◽  
Vol 6 (suppl A) ◽  
pp. 55-61 ◽  
Author(s):  
J. Klastersky ◽  
H. Gaya ◽  
S. H. Zinner ◽  
C. Bernard ◽  
J-C. Ryff ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
In Vivo Studies ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
And Staphylococcus Aureus

scholarly journals Synergy and remarkable specificity of antimicrobial peptides in vivo using a systematic knockout approach

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Mark Austin Hanson ◽  
Anna Dostálová ◽  
Camilla Ceroni ◽  
Mickael Poidevin ◽  
Shu Kondo ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Fungal Pathogens ◽  
Gene Editing ◽  
Cationic Peptides ◽  
Gram Negative Bacteria ◽  
Biological Processes ◽  
Gram Negative ◽  
Bacteria And Fungi

Antimicrobial peptides (AMPs) are host-encoded antibiotics that combat invading microorganisms. These short, cationic peptides have been implicated in many biological processes, primarily involving innate immunity. In vitro studies have shown AMPs kill bacteria and fungi at physiological concentrations, but little validation has been done in vivo. We utilized CRISPR gene editing to delete most known immune-inducible AMPs of Drosophila, namely: 4 Attacins, 2 Diptericins, Drosocin, Drosomycin, Metchnikowin and Defensin. Using individual and multiple knockouts, including flies lacking these ten AMP genes, we characterize the in vivo function of individual and groups of AMPs against diverse bacterial and fungal pathogens. We found that Drosophila AMPs act primarily against Gram-negative bacteria and fungi, contributing either additively or synergistically. We also describe remarkable specificity wherein certain AMPs contribute the bulk of microbicidal activity against specific pathogens, providing functional demonstrations of highly specific AMP-pathogen interactions in an in vivo setting.

scholarly journals Visualizing the Potential Impairment of Polymyxin B to Central Nervous System Through MR Susceptibility-Weighted Imaging

2021 ◽  
Vol 12 ◽  
Author(s):  
Ni Zhang ◽  
Lichong Zhu ◽  
Qiuhong Ouyang ◽  
Saisai Yue ◽  
Yichun Huang ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Polymyxin B ◽  
Susceptibility Weighted Imaging ◽  
Gram Negative Bacteria ◽  
Severe Toxicity ◽  
Gram Negative ◽  
The Impact

Polymyxin B (PMB) exert bactericidal effects on the cell wall of Gram-negative bacteria, leading to changes in the permeability of the cytoplasmic membrane and resulting in cell death, which is sensitive to the multi-resistant Gram-negative bacteria. However, the severe toxicity and adverse side effects largely hamper the clinical application of PMB. Although the molecular pathology of PMB neurotoxicity has been adequately studied at the cellular and molecular level. However, the impact of PMB on the physiological states of central nervous system in vivo may be quite different from that in vitro, which need to be further studied. Therefore, in the current study, the biocompatible ultra-uniform Fe3O4 nanoparticles were employed for noninvasively in vivo visualizing the potential impairment of PMB to the central nervous system. Systematic studies clearly reveal that the prepared Fe3O4 nanoparticles can serve as an appropriate magnetic resonance contrast agent with high transverse relaxivity and outstanding biosafety, which thus enables the following in vivo susceptibility-weighted imaging (SWI) studies on the PMB-treated mice models. As a result, it is first found that the blood-brain barrier (BBB) of mice may be impaired by successive PMB administration, displaying by the discrete punctate SWI signals distributed asymmetrically across brain regions in brain parenchyma. This result may pave a noninvasive approach for in-depth studies of PMB medication strategy, monitoring the BBB changes during PMB treatment, and even assessing the risk after PMB successive medication in multidrug-resistant Gram-negative bacterial infected patients from the perspective of medical imaging.

scholarly journals Elimination of Extracellular Adenosine Triphosphate for the Rapid Prediction of Quantitative Plate Counts in 24 h Time-Kill Studies against Carbapenem-Resistant Gram-Negative Bacteria

2020 ◽  
Vol 8 (10) ◽  
pp. 1489
Author(s):  
Yiying Cai ◽  
Jonathan J. Ng ◽  
Hui Leck ◽  
Jocelyn Q. Teo ◽  
Jia-Xuan Goh ◽  
...  
Keyword(s):  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Carbapenem Resistant ◽  
Infection Models ◽  
Rapid Prediction ◽  
Atp Bioluminescence ◽  
Plate Counts ◽  
Time Kill

Traditional in vitro time-kill studies (TKSs) require viable plating, which is tedious and time-consuming. We used ATP bioluminescence, with the removal of extracellular ATP (EC-ATP), as a surrogate for viable plating in TKSs against carbapenem-resistant Gram-negative bacteria (CR-GNB). Twenty-four-hour TKSs were conducted using eight clinical CR-GNB (two Escherichia coli, two Klebsiella spp., two Acinetobacter baumannii, two Pseudomonas aeruginosa) with multiple single and two-antibiotic combinations. ATP bioluminescence and viable counts were determined at each timepoint (0, 2, 4, 8, 24 h), with and without apyrase treatment. Correlation between ATP bioluminescence and viable counts was determined for apyrase-treated and non-apyrase-treated samples. Receiver operator characteristic curves were plotted to determine the optimal luminescence threshold to discriminate between inhibitory/non-inhibitory and bactericidal/non-bactericidal combinations, compared to viable counts. After treatment of bacteria with 2 U/mL apyrase for 15 min at 37 °C, correlation to viable counts was significantly higher compared to untreated samples (p < 0.01). Predictive accuracies of ATP bioluminescence were also significantly higher for apyrase-treated samples in distinguishing inhibitory (p < 0.01) and bactericidal (p = 0.03) combinations against CR-GNB compared to untreated samples, when all species were collectively analyzed. We found that ATP bioluminescence can potentially replace viable plating in TKS. Our assay also has applications in in vitro and in vivo infection models.

scholarly journals Antibacterial and Antibiotic Modifying Potential of Crude Extracts, Fractions, and Compounds from Acacia polyacantha Willd. against MDR Gram-Negative Bacteria

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Flora T. Mambe ◽  
Jean Na-Iya ◽  
Ghislain W. Fotso ◽  
Fred Ashu ◽  
Bathélémy Ngameni ◽  
...  
Keyword(s):  
Oleanolic Acid ◽  
Bacterial Infections ◽  
Efflux Pump ◽  
Synergistic Effects ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Efflux Pump Inhibitor ◽  
Gram Negative ◽  
Acacia Polyacantha

The present study aimed to assess the in vitro antibacterial and antibiotic modifying activities of methanol extracts prepared from the leaf (APL) and bark (APB) of Acacia polyacantha, fractions (APLa-d) and compounds isolated from APL against a panel of multidrug resistant (MDR) Gram-negative bacteria. Leaf extract was subjected to column chromatography for compounds isolation; antibacterial assays were performed on samples alone and with an efflux pump inhibitor (EPI), respectively, and several antibiotics on the tested bacteria. The phytochemical investigation of APL led to the isolation of stigmasterol (1), β-amyrin (2), 3-O-β-D-glucopyranosylstigmasterol (3), 3-O-methyl-D-chiro-inositol (4), epicatechin (5), quercetin-3-O-glucoside (6), 3-O-[β-D-xylopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (7), and 3-O-[β-galactopyranosyl-(1→4)-β-D-galactopyranosyl]-oleanolic acid (8). APL and APB had minimal inhibitory concentration (MIC) values ≤ 1024 μg/mL on 73.3% and 46.7% of the tested bacteria, respectively. APLb and APLd were effective against 88.9% of tested bacterial species with compound 8 showing the highest activity inhibiting 88.9% of tested bacteria. The EPI, phenylalanine-arginine-β-naphthylamide (PAßN), strongly improved the activity of APL, APLb, APLd, and compound 8 on all tested bacteria. Synergistic effects were obtained when APL and compounds 7 and 8 were combined with erythromycin (ERY), gentamycin (GEN), ciprofloxacin (CIP), and norfloxacin (NOR). The present study demonstrates the antibacterial potential of Acacia polyacantha and its constituents to combat bacterial infections alone or in combination with EPI.

Sign in / Sign up

Export Citation Format

Share Document