Putative virulence factors are released in association with membrane vesicles fromBurkholderia cepacia

2003 ◽  
Vol 49 (10) ◽  
pp. 613-624 ◽  
Author(s):  
Nick D Allan ◽  
Cora Kooi ◽  
Pamela A Sokol ◽  
Terry J Beveridge
Keyword(s):  
Virulence Factors ◽  
Burkholderia Cepacia ◽  
Sucrose Gradient ◽  
Membrane Vesicles ◽  
Normal Growth ◽  
Side Chain ◽  
Gram Negative Bacteria ◽  
Chain Polymer ◽  
New Strategy ◽  
Periplasmic Proteins

Like many other Gram-negative bacteria, Burkholderia cepacia naturally releases membrane vesicles (n-MVs) during normal growth. Through filtration and differential centrifugation, n-MVs from clinical isolates of the IIIa and V genomovars were isolated and their characteristics compared. Electron microscopy revealed that they were spherical, 30–220 nm in diameter, and bilayered. Virulence factors thought to play a role in pathogenicity (e.g., lipase, phospholipase-N, and protease, including a metalloprotease) were found associated with n-MVs, while peptidoglycan zymogram analysis also revealed 26, 28, 36, and 66 kDa peptidoglycan-degrading enzymes. n-MVs were often contaminated with flagella and pili when isolated by traditional methods, and a new strategy using a linear isopycnic sucrose gradient was utilized. For better characterization, this was applied to a representative genomovar IIIa strain (C5424) and showed that n-MVs consisted of a subset of specific outer membrane and periplasmic proteins as well as lipopoly saccharide possessing only a putative minor O-side chain polymer. This finding suggests that certain components are selected by B. cepacia during n-MV formation, and since some are putative virulence factors, this property could help deliver the factors to tissue, thereby aiding infection.Key words: membrane vesicles, virulence factors, Burkholderia cepacia, genomovar.

scholarly journals Secretin channel-interactors prevent antibiotic influx during type IV pili assembly in P. aeruginosa

2021 ◽  
Author(s):  
Hongbaek Cho ◽  
Oh Hyun Kwon ◽  
Joel W Sher ◽  
Bi-o Kim ◽  
You-Hee Cho
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Bacterial Pathogenesis ◽  
Type Iv Pili ◽  
Permeability Barrier ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Type Iv ◽  
Periplasmic Proteins ◽  
And Function

Type IV pili (T4P) are important virulence factors involved in host attachment and other aspects of bacterial pathogenesis. In Gram-negative bacteria, the T4P filament is polymerized from pilin subunits at the platform complex in the inner membrane (IM) and exits the outer membrane (OM) through the OM secretin channel. Although it is essential for T4P assembly and function, the OM secretin complexes can potentially impair the permeability barrier function of the OM and allow the entry of antibiotics and other toxic molecules. The mechanism by which Gram-negative bacteria prevent secretin-mediated OM leakage is currently not well understood. Here, we report a discovery of SlkA and SlkB (PA5122 and PA5123) that prevent permeation of several classes of antibiotics through the secretin channel of Pseudomonas aeruginosa type IV pili. We found these periplasmic proteins interact with the OM secretin complex and prevent toxic molecules from entering through the channel when there is a problem in the assembly of the T4P IM subcomplexes or when docking between the OM and IM complexes is defective.

scholarly journals Acinetobacter baumannii Quorum sensing: A way to communicate and a target to eradicate

2021 ◽  
Vol 3 (2) ◽  
pp. 134-145
Author(s):  
Elkheloui Raja ◽  
Hamadi Fatima ◽  
Mimouni Rachida
Keyword(s):  
Quorum Sensing ◽  
Acinetobacter Baumannii ◽  
Virulence Factors ◽  
Bacterial Infections ◽  
Quorum Quenching ◽  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Chronic Infections ◽  
New Strategy

Quorum sensing is a communication system based on the actions of chemical signal molecules depending on the density of the cell population. These molecules are widely considered as effectors of the gene expression of several virulence factors. As a result, it has attracted a lot of attention because of its possible applicability as a target for treating infections. This review attempts to give a description of this system on gram negative bacteria specifically on Acinetobacter baumannii as an important nosocomial pathogen. Additionally, quorum sensing in biofilm will be also treated because it is considered as the origin of several chronic infections. Numerous studies have been carried out to prove the role of inhibitors in the disruption of quorum sensing, known as quorum quenching. Quorum quenching is a new strategy to eradicate bacterial infections due to the crucial intervention of quorum sensing in different virulence factors and particularly in the biofilm formation.

Porphyromonas gingivalisOuter Membrane Vesicles Exclusively Contain Outer Membrane and Periplasmic Proteins and Carry a Cargo Enriched with Virulence Factors

2014 ◽  
Vol 13 (5) ◽  
pp. 2420-2432 ◽  
Author(s):  
Paul D. Veith ◽  
Yu-Yen Chen ◽  
Dhana G. Gorasia ◽  
Dina Chen ◽  
Michelle D. Glew ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Virulence Factors ◽  
Membrane Vesicles ◽  
Periplasmic Proteins

Assemblies of D-peptides for Targeting Cell Nucleolus

2019 ◽  
Author(s):  
Huaimin Wang ◽  
Zhaoqianqi Feng ◽  
Weiyi Tan ◽  
Bing Xu
Keyword(s):  
Particle Morphology ◽  
Side Chain ◽  
Mechanism Study ◽  
Structural Analogue ◽  
Hydrophobic Residues ◽  
Subcellular Organelles ◽  
First Case ◽  
New Strategy ◽  
Peptide Derivative ◽  
Peptide Nanoparticles

<p>Selectively targeting cell nucleolus remains a challenge. Here we report the first case that D-peptides form membraneless molecular condensates with RNA for targeting cell nucleolus. A D-peptide derivative, enriched with lysine and hydrophobic residues, self-assembles to form nanoparticles, which enter cells through clathrin dependent endocytosis and mainly accumulate at cell nucleolus. Structural analogue of the D-peptide reveals that particle morphology of the assemblies, which depends on the side chain modification, favors the cellular uptake. Contrasting to those of the D-peptide, the assemblies of the corresponding L-enantiomer largely localize in cell lysosomes. Preliminary mechanism study suggests that the D-peptide nanoparticles interact with RNA to form membraneless condensates in the nucleolus, which further induces DNA damage and results in cell death. This work illustrates a new strategy for rationally designing supramolecular assemblies of D-peptides for targeting subcellular organelles.</p>

Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

2019 ◽  
Author(s):  
Jiajun Wang ◽  
Rémi Terrasse ◽  
Jayesh Arun Bafna ◽  
Lorraine Benier ◽  
Mathias Winterhalter
Keyword(s):  
Outer Membrane ◽  
Lipid Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Multi Drug Resistance ◽  
Gram Negative Bacteria ◽  
Membrane Channels ◽  
Gram Negative ◽  
Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from <i>Escherichia coli</i>, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (<i>k<sub>on</sub></i>) and lower dissociation (<i>k<sub>off</sub></i>) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

scholarly journals Clonal Clusters, Molecular Resistance Mechanisms and Virulence Factors of Gram-Negative Bacteria Isolated from Chronic Wounds in Ghana

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 339
Author(s):  
Denise Dekker ◽  
Frederik Pankok ◽  
Thorsten Thye ◽  
Stefan Taudien ◽  
Kwabena Oppong ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Virulence Factors ◽  
Iron Uptake ◽  
Chronic Wounds ◽  
Sub Saharan Africa ◽  
Gram Negative Bacteria ◽  
Beta Lactamase ◽  
Secretion Systems ◽  
Gram Negative ◽  
E Coli

Wound infections are common medical problems in sub-Saharan Africa but data on the molecular epidemiology are rare. Within this study we assessed the clonal lineages, resistance genes and virulence factors of Gram-negative bacteria isolated from Ghanaian patients with chronic wounds. From a previous study, 49 Pseudomonas aeruginosa, 21 Klebsiellapneumoniae complex members and 12 Escherichia coli were subjected to whole genome sequencing. Sequence analysis indicated high clonal diversity with only nine P. aeruginosa clusters comprising two strains each and one E. coli cluster comprising three strains with high phylogenetic relationship suggesting nosocomial transmission. Acquired beta-lactamase genes were observed in some isolates next to a broad spectrum of additional genetic resistance determinants. Phenotypical expression of extended-spectrum beta-lactamase activity in the Enterobacterales was associated with blaCTX-M-15 genes, which are frequent in Ghana. Frequently recorded virulence genes comprised genes related to invasion and iron-uptake in E. coli, genes related to adherence, iron-uptake, secretion systems and antiphagocytosis in P. aeruginosa and genes related to adherence, biofilm formation, immune evasion, iron-uptake and secretion systems in K. pneumonia complex. In summary, the study provides a piece in the puzzle of the molecular epidemiology of Gram-negative bacteria in chronic wounds in rural Ghana.

Ultrafast Energy Transfer and Enhanced Two-Photon Absorption in a Novel Porphyrin Side-Chain Polymer

2004 ◽  
Vol 21 (12) ◽  
pp. 2521-2524 ◽  
Author(s):  
Wang Hui ◽  
Huang Ya-Ping ◽  
Deng Li ◽  
Zhao Fu-Li ◽  
Lin Wei-Zhu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Photon Absorption ◽  
Side Chain ◽  
Chain Polymer ◽  
Two Photon Absorption ◽  
Two Photon
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