scholarly journals High-resolution experimental and computational electrophysiology reveals weak β-lactam binding events in the porin PorB

2018 ◽  
Author(s):  
Annika Bartsch ◽  
Salomé Llabrés ◽  
Florian Pein ◽  
Christof Kattner ◽  
Markus Schön ◽  
...  
Keyword(s):  
High Resolution ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Weak Binding ◽  
Lactam Antibiotic ◽  
The Face ◽  
Biomolecular Simulations ◽  
Flow Through ◽  
Computational Electrophysiology ◽  
Increased Activity

ABSTRACTThe permeation of most antibiotics through the outer membrane of Gram-negative bacteria occurs through porin channels. To design drugs with increased activity against Gram-negative bacteria in the face of the antibiotic resistance crisis, the strict constraints on the physicochemical properties of the permeants imposed by these channels must be better understood. Here we show that a combination of high-resolution electrophysiology, new noise-filtering analysis protocols and atomistic biomolecular simulations reveals weak binding events between the β-lactam antibiotic ampicillin and the porin PorB from the pathogenic bacteriumNeisseria meningitidis. In particular, an asymmetry often seen in the electrophysiological characteristics of ligand-bound channels is utilised to characterise the binding site and molecular interactions in detail, based on the principles of electro-osmotic flow through the channel. Our results provide a rationale for the determinants that govern the binding and permeation of zwitterionic antibiotics in anion-selective porin channels.

scholarly journals Effects of reducing beta-lactam antibiotic pressure on intestinal colonization of antibiotic-resistant gram-negative bacteria

2009 ◽  
Vol 36 (3) ◽  
pp. 512-519 ◽  
Author(s):  
Saskia Nijssen ◽  
Ad Fluit ◽  
David van de Vijver ◽  
Janetta Top ◽  
Rob Willems ◽  
...  
Keyword(s):  
Gram Negative Bacteria ◽  
Intestinal Colonization ◽  
Beta Lactam ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Beta Lactam Antibiotic ◽  
Lactam Antibiotic

scholarly journals Modulation of the Neisseria gonorrhoeae drug efflux conduit MtrE

2017 ◽  
Author(s):  
Giulia Tamburrino ◽  
Salomé Llabrés ◽  
Owen N. Vickery ◽  
Samantha J. Pitt ◽  
Ulrich Zachariae
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Gram Negative Bacteria ◽  
Membrane Component ◽  
Gram Negative ◽  
Membrane Fusion Protein ◽  
Binding Interface ◽  
Open Conformation ◽  
Computational Electrophysiology ◽  
Maximum Conductance

ABSTRACTWidespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques. Our in vitro results show that MtrE can be regulated by periplasmic binding events and that the interaction between MtrE and MtrC is sufficient to stabilize this complex in an open state. In contrast to other efflux conduits, the open complex only displays a slight preference for cations. The maximum conductance we obtain in the in vitro recordings is comparable to that seen in our computational electrophysiology simulations conducted on the MtrE crystal structure, indicating that this state may reflect a physiologically relevant open conformation of MtrE. Our results suggest that the MtrC/E binding interface is an important modulator of MtrE function, which could potentially be targeted by new efflux inhibitors.

Perceiving the chemical language of Gram-negative bacteria: listening by high-resolution mass spectrometry

2012 ◽  
Vol 405 (2-3) ◽  
pp. 493-507 ◽  
Author(s):  
Tommaso R. I. Cataldi ◽  
Giuliana Bianco ◽  
Juliano Fonseca ◽  
Philippe Schmitt-Kopplin
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
High Resolution Mass Spectrometry ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
High Resolution Mass ◽  
Chemical Language ◽  
Resolution Mass

scholarly journals TonB dependent uptake of β-lactam antibiotics in the opportunistic human pathogen Stenotrophomonas maltophilia

2019 ◽  
Author(s):  
Karina Calvopiña ◽  
Punyawee Dulyayangkul ◽  
Kate J. Heesom ◽  
Matthew B. Avison
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Cross Resistance ◽  
Gram Negative Bacteria ◽  
Potential Utility ◽  
Human Pathogen ◽  
Gram Negative ◽  
Outer Membrane Porins ◽  
Lactam Antibiotic ◽  
Energy Transducer ◽  
Opportunistic Human Pathogen

AbstractThe β-lactam antibiotic ceftazidime is one of only a handful of drugs with proven clinical efficacy against the opportunistic human pathogen Stenotrophomonas maltophilia, Here, we show that mutations in the energy transducer TonB, encoded by smlt0009 in S. maltophilia, confer ceftazidime resistance. This breaks the dogma that β-lactams enter Gram-negative bacteria only by passive diffusion through outer membrane porins. By confirming cross-resistance of Smlt0009 mutants with a siderophore-conjugated lactivicin antibiotic, we reveal that attempts to improve penetration of antimicrobials into Gram negative bacteria by conjugating them with TonB substrates is likely to select β-lactam resistance in S. maltophilia, increasing its clinical threat. Furthermore, we show that S. maltophilia clinical isolates that have an Smlt0009 mutation already exist. Remarkably, therefore, β-lactam use is already eroding the potential utility of currently experimental siderophore-conjugated antimicrobials against this species.

In vitro studies of moxalactam (LY127935), a new beta-lactam antibiotic with significant activity against gram-negative bacteria

Infection ◽  
1980 ◽  
Vol 8 (S3) ◽  
pp. S261-S267 ◽  
Author(s):  
A. DeMaria ◽  
W. R. McCabe ◽  
J. O. Klein ◽  
W. R. McCabe
Keyword(s):  
In Vitro Studies ◽  
Gram Negative Bacteria ◽  
Significant Activity ◽  
Beta Lactam ◽  
Gram Negative ◽  
Beta Lactam Antibiotic ◽  
Lactam Antibiotic

Aminoglycoside Antibiotics in the Treatment of Otologic Infections

1981 ◽  
Vol 89 (5) ◽  
pp. 705-709 ◽  
Author(s):  
Gregory J. Matz ◽  
Stephen A. Lerner ◽  
Elisabeth F. Lanzl
Keyword(s):  
Central Nervous System ◽  
Aminoglycoside Antibiotics ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Malignant External Otitis ◽  
Lactam Antibiotic ◽  
Ear Infections ◽  
Gram Negative Organisms ◽  
Susceptibility Tests ◽  
Therapeutic Doses

Aminoglycoside antibiotics can be used successfully in the treatment of otologic infections caused by gram-negative bacteria. They can be particularly valuable, sometimes in combination with a β-lactam antibiotic such as carbenicillin, in malignant external otitis, acute middle ear infections caused by gram-negative organisms, and central nervous system complications of cholesteatomas. On the basis of susceptibility tests and of the pharmacology of these drugs, we administer appropriate therapeutic doses of one of the following antibiotics: Kanamycin, gentamicin, tobramycin, or amikacin. All of these drugs may be ototoxic and nephrotoxic.

scholarly journals The time course of hydrolysis of a β-lactam antibiotic by intact gram-negative bacteria possessing a periplasmic β-lactamase

1987 ◽  
Vol 244 (3) ◽  
pp. 509-513 ◽  
Author(s):  
W W Nichols
Keyword(s):  
Time Course ◽  
Decay Constant ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Beta Lactam ◽  
Intact Cells ◽  
Gram Negative ◽  
First Order ◽  
Lactam Antibiotic ◽  
Hydrolysis Of

An equation is derived from first principles for describing the change in concentration with time of a beta-lactam antibiotic in the presence of intact Gram-negative bacteria possessing a beta-lactamase located in the periplasmic space. The equation predicts a first-order decline in beta-lactam concentration of the form [S] = [Si]e lambda t, where [S] is the exogenous concentration of beta-lactam, [Si] is the value of [S] at time zero, t is the time from mixing of cells and antibiotic and lambda (less than 0) is the decay constant. The value of lambda is exactly described by the theory in terms of experimentally measurable quantities. Quantitative data concerning cephaloridine hydrolysis by intact cells of Haemophilus influenzae agreed well with the theory, as did data concerning the uptake of 2-nitrophenyl galactoside by intact cells of Escherichia coli. Cephalosporin C hydrolysis by intact cells of Pseudomonas aeruginosa did not progress as predicted by the theory. The theory is applicable to any substrate which is acted on by an enzyme that is located solely in the periplasmic space and that obeys the Michaelis-Menten equation of enzyme kinetics.

Bacterial-Mucosal Cell Junctional Complexes

1974 ◽  
Vol 32 ◽  
pp. 144-145
Author(s):  
Roger C. Wagner
Keyword(s):  
Intestinal Wall ◽  
Rat Colon ◽  
Mucosal Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Mucosal Cells ◽  
Mucosal Lining ◽  
Degenerative Alterations ◽  
Junctional Complexes ◽  
Intestinal Mucosal Cells

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

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