scholarly journals Studies on the Mode of Action of Reutericyclin

2003 ◽  
Vol 69 (2) ◽  
pp. 1305-1307 ◽  
Author(s):  
Michael G. Gänzle ◽  
Rudi F. Vogel
Keyword(s):  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Large Molecules ◽  
Proton Potential

ABSTRACT The mode of action of reutericyclin was determined with fluorescent dyes that probed the permeability of the cytoplasmic membrane by large molecules, protons, and potassium. A comparison of reutericyclin activity with those of nisin, nigericin, and valinomycin demonstrated that reutericyclin does not form pores but selectively dissipates the transmembrane proton potential.

Calcium ion imaging in plant cells

1993 ◽  
Vol 51 ◽  
pp. 132-133
Author(s):  
Peter K. Hepler ◽  
Dale A. Callaham
Keyword(s):  
Plant Cell Wall ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Free Acid ◽  
Methyl Esters ◽  
Free Calcium ◽  
Local Concentration ◽  
Ion Imaging ◽  
Membrane Compartments ◽  
Free Acid Form

Calcium ions (Ca) participate in many signal transduction processes, and for that reason it is important to determine where these ions are located within the living cell, and when and to what extent they change their local concentration. Of the different Ca-specific indicators, the fluorescent dyes, developed by Grynkiewicz et al. (1), have proved most efficacious, however, their use on plants has met with several problems (2). First, the dyes as acetoxy-methyl esters are often cleaved by extracellular esterases in the plant cell wall, and thus they do not enter the cell. Second, if the dye crosses the plasma membrane it may continue into non-cytoplasmic membrane compartments. Third, even if cleaved by esterases in the cytoplasm, or introduced as the free acid into the cytoplasmic compartment, the dyes often become quickly sequestered into vacuoles and organelles, or extruded from the cell. Finally, the free acid form of the dye readily complexes with proteins reducing its ability to detect free calcium. All these problems lead to an erroneous measurement of calcium (2).

Bactericidal action of peptide antibiotic AS-48 against Escherichia coli K-12

1989 ◽  
Vol 35 (2) ◽  
pp. 318-321 ◽  
Author(s):  
A. Gálvez ◽  
E. Valdivia ◽  
M. Martínez ◽  
M. Maqueda
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Cell Growth ◽  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Peptide Antibiotic ◽  
Biosynthetic Pathways ◽  
Bactericidal Action ◽  
Cell Wall Synthesis ◽  
K 12

Peptide antibiotic AS-48 exerts a bactericidal mode of action on exponential cultures of Escherichia coli K-12 through a multi-hit kinetics interaction. AS-48 causes a parallel and gradual cessation of all biosynthetic pathways monitored (protein, RNA, DNA, and cell wall synthesis), the rate of incorporation of labeled precursors, the rate of O2 consumption, and cell growth. These effects have been attributed to alterations of cytoplasmic membrane functions.Key words: Escherichia coli, peptide antibiotic, bactericide.

Assessment of the mode of action of polyhexamethylene biguanide against Listeria innocua by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis

2012 ◽  
Vol 58 (12) ◽  
pp. 1353-1361 ◽  
Author(s):  
Elise Chadeau ◽  
Emilie Dumas ◽  
Isabelle Adt ◽  
Pascal Degraeve ◽  
Claude Noël ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Fluorescence Anisotropy ◽  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Membrane Lipid ◽  
Listeria Innocua ◽  
Membrane Phospholipids ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Polyhexamethylene Biguanide ◽  
Membrane Lipid Bilayer

Polyhexamethylene biguanide (PHMB) is a cationic biocide. The antibacterial mode of action of PHMB (at concentrations not exceeding its minimal inhibitory concentration) upon Listeria innocua LRGIA 01 was investigated by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis. Fourier transformed infrared spectra of bacteria treated with or without PHMB presented some differences in the lipids region: the CH2/CH3 (2924 cm–1/2960 cm–1) band areas ratio significantly increased in the presence of PHMB. Since this ratio generally reflects membrane phospholipids and membrane microenvironment of the cells, these results suggest that PHMB molecules interact with membrane phospholipids and, thus, affect membrane fluidity and conformation. To assess the hypothesis of PHMB interaction with L. innocua membrane phospholipids and to clarify the PHMB mode of action, we performed fluorescence anisotropy experiments. Two probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative 1-[4-(trimethyl-amino)-phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), were used. DPH and TMA-DPH incorporate inside and at the surface of the cytoplasmic membrane, respectively. When PHMB was added, an increase of TMA-DPH fluorescence anisotropy was observed, but no changes of DPH fluorescence anisotropy occurred. These results are consistent with the hypothesis that PHMB molecules perturb L. innocua LRGIA 01 cytoplasmic membrane by interacting with the first layer of the membrane lipid bilayer.

SC5005 dissipates the membrane potential to kill Staphylococcus aureus persisters without detectable resistance

2021 ◽  
Author(s):  
Chieh-Hsien Lu ◽  
Chung-Wai Shiau ◽  
Yung-Chi Chang ◽  
Hsiu-Ni Kung ◽  
Jui-Ching Wu ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Resistance Development ◽  
Antibiotic Resistant ◽  
Atp Production ◽  
The Past ◽  
Ht 29

Abstract Objectives In the past few decades, multiple-antibiotic-resistant Staphylococcus aureus has emerged and quickly spread in hospitals and communities worldwide. Additionally, the formation of antibiotic-tolerant persisters and biofilms further reduces treatment efficacy. Previously, we identified a sorafenib derivative, SC5005, with bactericidal activity against MRSA in vitro and in vivo. Here, we sought to elucidate the resistance status, mode of action and anti-persister activity of this compound. Methods The propensity of S. aureus to develop SC5005 resistance was evaluated by assessment of spontaneous resistance and by multi-passage selection. The mode of action of SC5005 was investigated using macromolecular synthesis, LIVE/DEAD and ATPlite assays and DiOC2(3) staining. The effect of SC5005 on the mammalian cytoplasmic membrane was measured using haemolytic and lactate dehydrogenase (LDH) assays and flow cytometry. Results SC5005 depolarized and permeabilized the bacterial cytoplasmic membrane, leading to reduced ATP production. Because of this mode of action, no resistance of S. aureus to SC5005 was observed after constant exposure to sub-lethal concentrations for 200 passages. The membrane-perturbing activity of SC5005 was specific to bacteria, as no significant haemolysis or release of LDH from human HT-29 cells was detected. Additionally, compared with other bactericidal antibiotics, SC5005 exhibited superior activity in eradicating both planktonic and biofilm-embedded S. aureus persisters. Conclusions Because of its low propensity for resistance development and potent persister-eradicating activity, SC5005 is a promising lead compound for developing new therapies for biofilm-related infections caused by S. aureus.

Mode of Action of Linenscin OC2 againstListeria innocua

1998 ◽  
Vol 64 (9) ◽  
pp. 3416-3421 ◽  
Author(s):  
Catherine Boucabeille ◽  
Lucienne Letellier ◽  
Jean-Marc Simonet ◽  
Gilles Henckes
Keyword(s):  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Environmental Parameters ◽  
Low Doses ◽  
Gram Positive Bacteria ◽  
Hydrocarbon Chains ◽  
Energetic State ◽  
Outer Membrane Permeability ◽  
Hydrolysis Of ◽  
Small Hydrophobic

ABSTRACT Linenscin OC2 is a small hydrophobic substance produced by the orange cheese coryneform bacterium Brevibacterium linensOC2. Linenscin OC2 inhibits growth of gram-negative bacteria with an altered outer membrane permeability and gram-positive bacteria. It is also able to lyse eucaryotic cells. The mode of action of linenscin OC2 on the Listeria innocua cytoplasmic membrane and the effects of environmental parameters were investigated. Addition of low doses of linenscin OC2 resulted in an immediate perturbation of the permeability properties of the cytoplasmic membrane and of the bacterial energetic state. Linenscin OC2 induced a loss of cytoplasmic potassium, depolarization of the cytoplasmic membrane, complete hydrolysis of internal ATP, efflux of inorganic phosphate, and transient increase in oxygen consumption. Potassium loss occurred in the absence of a proton motive force and was severely reduced at low temperatures, presumably as a result of increased ordering of the lipid hydrocarbon chains of the cytoplasmic membrane. We propose that linenscin OC2 interacts with the cytoplasmic membrane and that the permeability changes observed at low doses reflect the formation of pore-like structures in this membrane.

scholarly journals Transport of C4-Dicarboxylates inWolinella succinogenes

2000 ◽  
Vol 182 (20) ◽  
pp. 5757-5764 ◽  
Author(s):  
Roland Ullmann ◽  
Roland Gross ◽  
Jörg Simon ◽  
Gottfried Unden ◽  
Achim Kröger
Keyword(s):  
Carbon Source ◽  
Cytoplasmic Membrane ◽  
Anaerobic Respiration ◽  
Molar Ratio ◽  
Nitrate Respiration ◽  
Gene Products ◽  
Dicarboxylate Transport ◽  
Proton Potential ◽  
Fumarate Respiration ◽  
Cytoplasmic Side

ABSTRACT C4-dicarboxylate transport is a prerequisite for anaerobic respiration with fumarate in Wolinella succinogenes, since the substrate site of fumarate reductase is oriented towards the cytoplasmic side of the membrane. W. succinogenes was found to transport C4-dicarboxylates (fumarate, succinate, malate, and aspartate) across the cytoplasmic membrane by antiport and uniport mechanisms. The electrogenic uniport resulted in dicarboxylate accumulation driven by anaerobic respiration. The molar ratio of internal to external dicarboxylate concentration was up to 103. The dicarboxylate antiport was either electrogenic or electroneutral. The electroneutral antiport required the presence of internal Na+, whereas the electrogenic antiport also operated in the absence of Na+. In the absence of Na+, no electrochemical proton potential (Δp) was measured across the membrane of cells catalyzing fumarate respiration. This suggests that the proton potential generated by fumarate respiration is dissipated by the concomitant electrogenic dicarboxylate antiport. Three gene loci (dcuA,dcuB, and dctPQM) encoding putative C4-dicarboxylate transporters were identified on the genome of W. succinogenes. The predicted gene products ofdcuA and dcuB are similar to the Dcu transporters that are involved in the fumarate respiration ofEscherichia coli with external C4-dicarboxylates. The genes dctP, -Q, and -M probably encode a binding-protein-dependent secondary uptake transporter for dicarboxylates. A mutant (DcuA− DcuB−) ofW. succinogenes lacking the intact dcuA anddcuB genes grew by nitrate respiration with succinate as the carbon source but did not grow by fumarate respiration with fumarate, malate, or aspartate as substrates. The DcuA−, DcuB−, and DctQM− mutants grew by fumarate respiration as well as by nitrate respiration with succinate as the carbon source. Cells of the DcuA− DcuB−mutant performed fumarate respiration without generating a proton potential even in the presence of Na+. This explains why the DcuA− DcuB− mutant does not grow by fumarate respiration. Growth by fumarate respiration appears to depend on the function of the Na+-dependent, electroneutral dicarboxylate antiport which is catalyzed exclusively by the Dcu transporters. Dicarboxylate transport via the electrogenic uniport is probably catalyzed by the DctPQM transporter and by a fourth, unknown transporter that may also operate as an electrogenic antiporter.

scholarly journals Bridging the Antimicrobial Activity of Two Lactoferricin Derivatives in E. coli and Lipid-Only Membranes

2021 ◽  
Vol 3 ◽  
Author(s):  
Lisa Marx ◽  
Enrico F. Semeraro ◽  
Johannes Mandl ◽  
Johannes Kremser ◽  
Moritz P. Frewein ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Cytoplasmic Membrane ◽  
Fluorescent Dyes ◽  
Tryptophan Fluorescence ◽  
X Ray ◽  
E Coli ◽  
Molar Ratios ◽  
X Ray Scattering ◽  
Membrane Mimics ◽  
Peptide Partitioning

We coupled the antimicrobial activity of two well-studied lactoferricin derivatives, LF11-215 and LF11-324, in Escherichia coli and different lipid-only mimics of its cytoplasmic membrane using a common thermodynamic framework for peptide partitioning. In particular, we combined an improved analysis of microdilution assays with ζ-potential measurements, which allowed us to discriminate between the maximum number of surface-adsorbed peptides and peptides fully partitioned into the bacteria. At the same time, we measured the partitioning of the peptides into vesicles composed of phosphatidylethanolamine (PE), phosphatidylgylcerol (PG), and cardiolipin (CL) mixtures using tryptophan fluorescence and determined their membrane activity using a dye leakage assay and small-angle X-ray scattering. We found that the vast majority of LF11-215 and LF11-324 readily enter inner bacterial compartments, whereas only 1−5% remain surface bound. We observed comparable membrane binding of both peptides in membrane mimics containing PE and different molar ratios of PG and CL. The peptides' activity caused a concentration-dependent dye leakage in all studied membrane mimics; however, it also led to the formation of large aggregates, part of which contained collapsed multibilayers with sandwiched peptides in the interstitial space between membranes. This effect was least pronounced in pure PG vesicles, requiring also the highest peptide concentration to induce membrane permeabilization. In PE-containing systems, we additionally observed an effective shielding of the fluorescent dyes from leakage even at highest peptide concentrations, suggesting a coupling of the peptide activity to vesicle fusion, being mediated by the intrinsic lipid curvatures of PE and CL. Our results thus show that LF11-215 and LF11-324 effectively target inner bacterial components, while the stored elastic stress makes membranes more vulnerable to peptide translocation.

Mode of action of thuricin S, a new class IId bacteriocin fromBacillus thuringiensis

2010 ◽  
Vol 56 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Sonia Chehimi ◽  
Anne-Marie Pons ◽  
Sophie Sablé ◽  
Mohamed-Rabeh Hajlaoui ◽  
Férid Limam
Keyword(s):  
Bacillus Thuringiensis ◽  
Mode Of Action ◽  
Transmembrane Potential ◽  
Cytoplasmic Membrane ◽  
Morphological Changes ◽  
Membrane Integrity ◽  
Bactericidal Effect ◽  
New Class ◽  
Bacillus Thuringiensis Subsp ◽  
Scanning Electron

Different methods were used to elucidate the mode of action of thuricin S, a new class IId bacteriocin produced by Bacillus thuringiensis subsp. entomocidus HD198. According to cell viability tests, thuricin S was shown to exert a bactericidal effect on the sensitive cells of Bacillus thuringiensis subsp. darmastadiensis 10T. The use of the fluorescent probe 3,3′-dipropylthiadicarbocyanine iodide as an indicator proved that thuricin S interacts with the cytoplasmic membrane to dissipate the transmembrane potential. It was also demonstrated that thuricin S acts as a pore-forming bacteriocin, since it allows the nonpermeable stain propidium iodide to enter the cells. The loss of membrane integrity and the morphological changes in sensitive cells were visualized by scanning electron microscopy.

Effect of Butylated Hydroxyanisole on the Cytoplasmic Membrane of Staphylococcus aureus Wood 46

1983 ◽  
Vol 46 (3) ◽  
pp. 206-209 ◽  
Author(s):  
RICHARD DEGRÉ ◽  
MICHEL SYLVESTRE
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Mode Of Action ◽  
Cytoplasmic Membrane ◽  
Active Agent ◽  
Phenolic Antioxidant ◽  
Butylated Hydroxyanisole

The antimicrobial mode of action of the phenolic antioxidant butylated hydroxyanisole (BHA) against Staphylococcus aureus Wood 46 was examined. The compound was taken up very rapidly by the cells and adsorption was completed within 15 min. Exposure of a growing suspension to 50 μg of BHA/ml was bactericidal, but this concentration had no significant effect on the viability of a non-growing suspension. However, concentrations over 100 μg/ml were lethal to the latter and this bactericidal activity was related to leakage of nucleotides. Protoplasts produced by lysostaphin treatment undergo lysis when exposed to concentrations as low as 25 μg/ml. A mutant resistant to 50 μg of BHA/ml adsorbed the same amount of BHA but protoplasts from this strain were less susceptible to lysis. It was concluded that BHA is a member-active agent.

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