scholarly journals Active Cytotoxic Necrotizing Factor 1 Associated with Outer Membrane Vesicles from Uropathogenic Escherichia coli

2006 ◽  
Vol 74 (4) ◽  
pp. 2022-2030 ◽  
Author(s):  
J. Clavin Kouokam ◽  
Sun Nyunt Wai ◽  
Maria Fällman ◽  
Ulrich Dobrindt ◽  
Jörg Hacker ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicle ◽  
Active Form ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Upec Strain ◽  
Cytotoxic Necrotizing Factor ◽  
Factor Type ◽  
Bacterial Cytoplasm

ABSTRACT Cytotoxic necrotizing factor type 1 (CNF1) is one of the virulence factors produced by uropathogenic Escherichia coli (UPEC). How this toxin is translocated from the bacterial cytoplasm to the surrounding environment is not well understood. Our data suggest that CNF1 may be regarded as a secreted protein, since it could be detected in culture supernatants. Furthermore, we found that CNF1 was tightly associated to outer membrane vesicles, suggesting that such vesicles play a role in the secretion of this protein. Interestingly, vesicle samples containing CNF1 could exert the effects known for this protein on HeLa cell cultures, showing that CNF1 is transported by vesicles in its active form. Taken together, our results strongly suggest that outer membrane vesicles could be a means for the bacteria to deliver CNF1 to the environment and to the infected tissue. In addition, our results indicate that the histone-like nucleoid structuring protein H-NS has a role in the downregulation of CNF1 production and that it affects the outer membrane vesicle release in UPEC strain J96.

scholarly journals Cytotoxic Necrotizing Factor Type 1 Delivered by Outer Membrane Vesicles of Uropathogenic Escherichia coli Attenuates Polymorphonuclear Leukocyte Antimicrobial Activity and Chemotaxis

2006 ◽  
Vol 74 (8) ◽  
pp. 4401-4408 ◽  
Author(s):  
Jon M. Davis ◽  
Humberto M. Carvalho ◽  
Susan B. Rasmussen ◽  
Alison D. O'Brien
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Single Amino Acid ◽  
Upec Strain ◽  
Cytotoxic Necrotizing Factor ◽  
Factor Type

ABSTRACT Cytotoxic necrotizing factor type 1 (CNF1), a toxin produced by many strains of uropathogenic Escherichia coli (UPEC), constitutively activates small GTPases of the Rho family by deamidating a single amino acid within these target proteins. Such activated GTPases not only stimulate actin polymerization within affected cells but also, as we previously reported, decrease membrane fluidity on mouse polymorphonuclear leukocytes (PMNs). In that same investigation we found that this diminished membrane movement impedes the clustering of the complement receptor CD11b/CD18 on PMNs and, in turn, decreases PMN phagocytic capacity and microbicidal activity on PMNs in direct contact with CNF1-expressing UPEC as well as on those in proximity to wild-type UPEC. The latter observation suggested to us that CNF1 is released from neighboring bacteria, although at the time of initiation of the study described here, no specific mechanism for export of CNF1 from UPEC had been described. Here we present evidence that CNF1 is released from the CNF1-expressing UPEC strain CP9 (serotype O4/H5/K54) in a complex with outer membrane vesicles (OMVs) and that these CNF1-bearing vesicles transfer biologically active CNF1 to PMNs and attenuate phagocyte function. Furthermore, we show that CNF1-bearing vesicles act in a dose-dependent fashion on PMNs to inhibit their chemotactic response to formyl-Met-Leu-Phe, while purified CNF1 does not. We conclude that OMVs provide a means for delivery of CNF1 from a UPEC strain to PMNs and thus negatively affect the efficacy of the acute inflammatory response to these organisms.

scholarly journals Outer Membrane Vesicle Production by Escherichia coli Is Independent of Membrane Instability

2006 ◽  
Vol 188 (15) ◽  
pp. 5385-5392 ◽  
Author(s):  
Amanda J. McBroom ◽  
Alexandra P. Johnson ◽  
Sreekanth Vemulapalli ◽  
Meta J. Kuehn
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Fold Increase ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Physiological Basis ◽  
Gram Negative

ABSTRACT It has been long noted that gram-negative bacteria produce outer membrane vesicles, and recent data demonstrate that vesicles released by pathogenic strains can transmit virulence factors to host cells. However, the mechanism of vesicle release has remained undetermined. This genetic study addresses whether these structures are merely a result of membrane instability or are formed by a more directed process. To elucidate the regulatory mechanisms and physiological basis of vesiculation, we conducted a screen in Escherichia coli to identify gene disruptions that caused vesicle over- or underproduction. Only a few low-vesiculation mutants and no null mutants were recovered, suggesting that vesiculation may be a fundamental characteristic of gram-negative bacterial growth. Gene disruptions were identified that caused differences in vesicle production ranging from a 5-fold decrease to a 200-fold increase relative to wild-type levels. These disruptions included loci governing outer membrane components and peptidoglycan synthesis as well as the σE cell envelope stress response. Mutations causing vesicle overproduction did not result in upregulation of the ompC gene encoding a major outer membrane protein. Detergent sensitivity, leakiness, and growth characteristics of the novel vesiculation mutant strains did not correlate with vesiculation levels, demonstrating that vesicle production is not predictive of envelope instability.

scholarly journals Comparative Analysis of Outer Membrane Vesicle Isolation Methods With an Escherichia coli tolA Mutant Reveals a Hypervesiculating Phenotype With Outer-Inner Membrane Vesicle Content

2021 ◽  
Vol 12 ◽  
Author(s):  
Shelby L. Reimer ◽  
Daniel R. Beniac ◽  
Shannon L. Hiebert ◽  
Timothy F. Booth ◽  
Patrick M. Chong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Size Distributions ◽  
Transmission Electron ◽  
Isolation Methods ◽  
Morphological Differences ◽  
K 12

Outer membrane vesicles (OMVs) produced by Gram-negative bacteria are mediators of cell survival and pathogenesis by facilitating virulence factor dissemination and resistance to antimicrobials. Studies of OMV properties often focus on hypervesiculating Escherichia coli mutants that have increased OMV production when compared to their corresponding wild-type (WT) strains. Currently, two conventional techniques, ultracentrifugation (UC) and ultradiafiltration (UF), are used interchangeably to isolate OMVs, however, there is concern that each technique may inadvertently alter the properties of isolated OMVs during study. To address this concern, we compared two OMV isolation methods, UC and UF, with respect to final OMV quantities, size distributions, and morphologies using a hypervesiculating Escherichia coli K-12 ΔtolA mutant. Nanoparticle tracking analysis (NTA) indicated that UC techniques result in lower vesicle yields compared to UF. However, UF permitted isolation of OMVs with smaller average sizes than UC, highlighting a potential OMV isolation size bias by each technique. Cryo-transmission electron microscopy (cryo-TEM) visualization of isolated OMVs revealed distinct morphological differences between WT and ΔtolA OMVs, where ΔtolA OMVs isolated by either UC or UF method possessed a greater proportion of OMVs with two or more membranes. Proteomic OMV analysis of WT and ΔtolA OMVs confirmed that ΔtolA enhances inner plasma membrane carryover in multi-lamellar OMVs. This study demonstrates that UC and UF are useful techniques for OMV isolation, where UF may be preferable due to faster isolation, higher OMV yields and enrichment of smaller sized vesicles.

scholarly journals A Suppressor of Cell Death Caused by the Loss of σE Downregulates Extracytoplasmic Stress Responses and Outer Membrane Vesicle Production in Escherichia coli

2006 ◽  
Vol 189 (5) ◽  
pp. 1523-1530 ◽  
Author(s):  
Julie E. Button ◽  
Thomas J. Silhavy ◽  
Natividad Ruiz
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Outer Membrane ◽  
Stress Responses ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Σ Factor

ABSTRACT When envelope biogenesis is compromised or damage to envelope components occurs, bacteria trigger signaling cascades, which lead to the production of proteins that combat such extracytoplasmic stresses. In Escherichia coli, there are three pathways known to deal with envelope stresses: the Bae, Cpx, and σE responses. Although the effectors of the Bae and Cpx responses are not essential in E. coli, the effector of the σE response, the sigma factor RpoE (σE), is essential for viability. However, mutations that suppress the lethality of an rpoE-null allele can be easily obtained, and here we describe how we have isolated at least four classes of these suppressors. We present the first description of one such suppressor class, loss-of-function mutations in ydcQ, a gene encoding a putative DNA-binding protein. In wild-type rpoE + strains, ydcQ mutants have two distinct phenotypes: extracytoplasmic stress responses are significantly downregulated, and the production of outer membrane vesicles is severely reduced. We present a model in which σE is not essential per se but, rather, we propose that rpoE mutant cells die, possibly because they overreact to the absence of this σ factor by triggering a cell death signal.

scholarly journals Proteome‐minimized outer membrane vesicles from Escherichia coli as a generalized vaccine platform

2021 ◽  
Vol 10 (4) ◽  
Author(s):  
Ilaria Zanella ◽  
Enrico König ◽  
Michele Tomasi ◽  
Assunta Gagliardi ◽  
Luca Frattini ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Vaccine Platform

scholarly journals Combining Augmented Radiotherapy and Immunotherapy through a Nano-Gold and Bacterial Outer-Membrane Vesicle Complex for the Treatment of Glioblastoma

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1661
Author(s):  
Mei-Hsiu Chen ◽  
Tse-Ying Liu ◽  
Yu-Chiao Chen ◽  
Ming-Hong Chen
Keyword(s):  
Outer Membrane ◽  
Membrane Vesicle ◽  
Glioma Cells ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
E Coli ◽  
Tumor Bearing ◽  
Nano Gold ◽  
Gl261 Cell

Glioblastoma, formerly known as glioblastoma multiforme (GBM), is refractory to existing adjuvant chemotherapy and radiotherapy. We successfully synthesized a complex, Au–OMV, with two specific nanoparticles: gold nanoparticles (AuNPs) and outer-membrane vesicles (OMVs) from E. coli. Au–OMV, when combined with radiotherapy, produced radiosensitizing and immuno-modulatory effects that successfully suppressed tumor growth in both subcutaneous G261 tumor-bearing and in situ (brain) tumor-bearing C57BL/6 mice. Longer survival was also noted with in situ tumor-bearing mice treated with Au–OMV and radiotherapy. The mechanisms for the successful treatment were evaluated. Intracellular reactive oxygen species (ROS) greatly increased in response to Au–OMV in combination with radiotherapy in G261 glioma cells. Furthermore, with a co-culture of G261 glioma cells and RAW 264.7 macrophages, we found that GL261 cell viability was related to chemotaxis of macrophages and TNF-α production.

Specific protein-membrane interactions promote packaging of metallo-β-lactamases into outer membrane vesicles

2021 ◽  
Author(s):  
Carolina López ◽  
Alessio Prunotto ◽  
Guillermo Bahr ◽  
Robert A. Bonomo ◽  
Lisandro J. González ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Electrostatic Interactions ◽  
Active Form ◽  
Membrane Vesicles ◽  
Specific Protein ◽  
Outer Membrane Vesicles ◽  
Soluble Enzyme ◽  
Membrane Interactions ◽  
Resistance Determinants ◽  
Protein Membrane

Outer membrane vesicles (OMVs) act as carriers of bacterial products such as plasmids and resistance determinants, including metallo-β-lactamases. The lipidated, membrane-anchored metallo-β-lactamase NDM-1 can be detected in Gram-negative OMVs. The soluble domain of NDM-1 also forms electrostatic interactions with the membrane. Herein, we show that these interactions promote its packaging into OMVs produced by Escherichia coli . We report that favorable electrostatic protein-membrane interactions are also at work in the soluble enzyme IMP-1, while being absent in VIM-2. These interactions correlate with an enhanced incorporation of IMP-1 compared to VIM-2 into OMVs. Disruption of these interactions in NDM-1 and IMP-1 impairs their inclusion into vesicles, confirming their role in defining the protein cargo in OMVs. These results also indicate that packaging of metallo-β-lactamases into vesicles in their active form is a common phenomenon that involves cargo selection based on specific molecular interactions.

scholarly journals Release of the type I secreted alpha-haemolysin via outer membrane vesicles from Escherichia coli

2006 ◽  
Vol 59 (1) ◽  
pp. 99-112 ◽  
Author(s):  
Carlos Balsalobre ◽  
Jose Manuel Silvan ◽  
Stina Berglund ◽  
Yoshimitsu Mizunoe ◽  
Bernt Eric Uhlin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Type I
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