scholarly journals TolA, TolB, and TolR Are Critical Cell Envelope Proteins of Salmonella Enterica Serovar Choleraesuis Affecting Cell Morphology, OMVs Production, and Virulence

2021 ◽  
Author(s):  
Quan Li ◽  
Zheng Li ◽  
Xia Fei ◽  
Yichen Tian ◽  
Guodong Zhou ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Cell Envelope ◽  
Membrane Integrity ◽  
Membrane Vesicles ◽  
High Sensitivity ◽  
Sodium Deoxycholate ◽  
Envelope Proteins ◽  
Outer Membrane Vesicles ◽  
Infection Model

Abstract The Tol-Pal system of Gram-negative bacteria is necessary for maintaining outer membrane integrity. It is a multiprotein complex of five envelope proteins, TolQ, TolR, TolA, TolB, and Pal. These proteins were first investigated in E. coli, and subsequently been identified in many other bacterial genera. However, the function of the Tol-Pal system in Salmonella Choleraesuis pathogenesis is still unclear. Here, we reported the role of three of these proteins in the phenotype and biology of S. Choleraesuis. We found that mutations in tolA, tolB, and tolR caused severe damage to the cell wall, which was supported by observing the microstructure of spherical forms, long chains, flagella defects, and membrane blebbing. We confirmed that all the mutants significantly decreased S. Choleraesuis survival when exposed to sodium deoxycholate and exhibited a high sensitivity to vancomycin, which may be explained by the disruption of envelope integrity. In addition, tolA, tolB, and tolR mutants displayed attenuated virulence in a mouse infection model. This could be interpreted as a series of defective phenotypes in the mutants, such as severe defects in envelope integrity, growth, and motility. Further investigation showed that all the genes participate in outer membrane vesicles (OMVs) biogenesis. Interestingly, immunization with OMVs from ΔtolB efficiently enhanced murine viability in contrast to OMVs from the wild-type S. Choleraesuis, suggesting its potential use in vaccination strategies. Collectively, this study provides an insight into the biological role of the S. Choleraesuis Tol-Pal system.

scholarly journals The Mutation of Conservative Asp268 Residue in the Peptidoglycan-Associated Domain of the OmpA Protein Affects Multiple Acinetobacter baumannii Virulence Characteristics

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1972 ◽  
Author(s):  
Jūratė Skerniškytė ◽  
Emilija Karazijaitė ◽  
Julien Deschamps ◽  
Renatas Krasauskas ◽  
Romain Briandet ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Protein A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Clinical Strain ◽  
Infection Model ◽  
Terminal Domain ◽  
Ompa Protein

Acinetobacter baumannii is a nosocomial human pathogen of increasing concern due to its multidrug resistance profile. The outer membrane protein A (OmpA) is an abundant bacterial cell surface component involved in A. baumannii pathogenesis. It has been shown that the C-terminal domain of OmpA is located in the periplasm and non-covalently associates with the peptidoglycan layer via two conserved amino acids, thereby anchoring OmpA to the cell wall. Here, we investigated the role of one of the respective residues, D268 in OmpA of A. baumannii clinical strain Ab169, on its virulence characteristics by complementing the ΔompA mutant with the plasmid-borne ompAD268A allele. We show that while restoring the impaired biofilm formation of the ΔompA strain, the Ab169ompAD268A mutant tended to form bacterial filaments, indicating the abnormalities in cell division. Moreover, the Ab169 OmpA D268-mediated association to peptidoglycan was required for the manifestation of twitching motility, desiccation resistance, serum-induced killing, adhesion to epithelial cells and virulence in a nematode infection model, although it was dispensable for the uptake of β-lactam antibiotics by outer membrane vesicles. Overall, the results of this study demonstrate that the OmpA C-terminal domain-mediated association to peptidoglycan is critical for a number of virulent properties displayed by A. baumannii outside and within the host.

scholarly journals Pal Lipoprotein of Escherichia coli Plays a Major Role in Outer Membrane Integrity

2002 ◽  
Vol 184 (3) ◽  
pp. 754-759 ◽  
Author(s):  
Eric Cascales ◽  
Alain Bernadac ◽  
Marthe Gavioli ◽  
Jean-Claude Lazzaroni ◽  
Roland Lloubes
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Membrane Integrity ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Permeability Barrier ◽  
Oligomeric State ◽  
Periplasmic Proteins ◽  
Outer Membrane Permeability

ABSTRACT The Tol-Pal system of gram-negative bacteria is composed of five proteins. TolA, TolQ, and TolR are inner membrane proteins, TolB is a periplasmic protein, and Pal, the peptidoglycan-associated lipoprotein, is anchored to the outer membrane. In this study, the roles of Pal and major lipoprotein Lpp were compared in Escherichia coli. lpp and tol-pal mutations have previously been found to perturb the outer membrane permeability barrier and to cause the release of periplasmic proteins and the formation of outer membrane vesicles. In this study, we showed that the overproduction of Pal is able to restore the outer membrane integrity of an lpp strain but that overproduced Lpp has no effect in a pal strain. Together with the previously reported observation that overproduced TolA complements an lpp but not a pal strain, these results indicate that the cell envelope integrity is efficiently stabilized by an epistatic Tol-Pal system linking inner and outer membranes. The density of Pal was measured and found to be lower than that of Lpp. However, Pal was present in larger amounts compared to TolA and TolR proteins. The oligomeric state of Pal was determined and a new interaction between Pal and Lpp was demonstrated.

scholarly journals Bacterial glycoengineering as a biosynthetic route to customized glycomolecules

2017 ◽  
Author(s):  
Laura E. Yates ◽  
Dominic C. Mills ◽  
Matthew P. DeLisa
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Recombinant Expression ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Living Systems ◽  
Conjugate Vaccines ◽  
Biosynthetic Machinery ◽  
Opening Up

AbstractBacteria have garnered increased interest in recent years as a platform for the biosynthesis of a variety of glycomolecules such as soluble oligosaccharides, surface-exposed carbohydrates and glycoproteins. The ability to flexibly engineer commonly used laboratory species such asEscherichia colito efficiently synthesize non-native sugar structures by recombinant expression of enzymes from various carbohydrate biosynthesis pathways has allowed for the facile generation of important products such as conjugate vaccines, glycosylated outer membrane vesicles, and a variety of other research reagents for studying and understanding the role of glycans in living systems. This chapter highlights some of the key discoveries and technologies for equipping bacteria with the requisite biosynthetic machinery to generate such products. As the bacterial glyco-toolbox continues to grow, these technologies are expected to expand the range of glycomolecules produced recombinantly in bacterial systems, thereby opening up this platform to an even larger number of applications.

scholarly journals Escherichia coli tol-pal Mutants Form Outer Membrane Vesicles

1998 ◽  
Vol 180 (18) ◽  
pp. 4872-4878 ◽  
Author(s):  
Alain Bernadac ◽  
Marthe Gavioli ◽  
Jean-Claude Lazzaroni ◽  
Satish Raina ◽  
Roland Lloubès
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Integrity ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Extracellular Medium ◽  
Solid Media ◽  
Outer Membrane Lipoprotein ◽  
Periplasmic Proteins ◽  
Outer Membrane Permeability

ABSTRACT Mutations in the tol-pal genes induce pleiotropic effects such as release of periplasmic proteins into the extracellular medium and hypersensitivity to drugs and detergents. Other outer membrane defective strains such as tolC, lpp, and rfa mutations are also altered in their outer membrane permeability. In this study, electron microscopy and Western blot analyses were used to show that strains with mutations in each of thetol-pal genes formed outer membrane vesicles after growth in standard liquid or solid media. This phenotype was not observed intolC and rfaD cells in the same conditions. AtolA deletion in three different Escherichia coli strains was shown to lead to elevated amounts of vesicles. These results, together with plasmid complementation experiments, indicated that the formation of vesicles resulted from the defect of any of the Tol-Pal proteins. The vesicles contained outer membrane trimeric porins correctly exposed at the cell surface. Pal outer membrane lipoprotein was also immunodetected in the vesicle fraction oftol strains. The results are discussed in view of the role of the Tol-Pal transenvelope proteins in maintaining outer membrane integrity by contributing to target or integrate newly synthesized components of this structure.

scholarly journals The Importance of Porins and β-Lactamase in Outer Membrane Vesicles on the Hydrolysis of β-Lactam Antibiotics

2020 ◽  
Vol 21 (8) ◽  
pp. 2822 ◽  
Author(s):  
Si Won Kim ◽  
Jung Seok Lee ◽  
Seong Bin Park ◽  
Ae Rin Lee ◽  
Jae Wook Jung ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Defense Mechanisms ◽  
Antibacterial Properties ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
E Coli ◽  
Lactam Antibiotic ◽  
Hydrolysis Of ◽  
Degradation Ability

Gram-negative bacteria have an outer membrane inhibiting the entry of antibiotics. Porins, found within the outer membrane, are involved in regulating the permeability of β-lactam antibiotics. β-lactamases are enzymes that are able to inactivate the antibacterial properties of β-lactam antibiotics. Interestingly, porins and β-lactamase are found in outer membrane vesicles (OMVs) of β-lactam-resistant Escherichia coli and may be involved in the survival of susceptible strains of E. coli in the presence of antibiotics, through the hydrolysis of the β-lactam antibiotic. In this study, OMVs isolated from β-lactam-resistant E. coli and from mutants, lacking porin or β-lactamase, were evaluated to establish if the porins or β-lactamase in OMVs were involved in the degradation of β-lactam antibiotics. OMVs isolated from E. coli deficient in β-lactamase did not show any degradation ability against β-lactam antibiotics, while OMVs lacking OmpC or OmpF showed significantly lower levels of hydrolyzing activity than OMVs from parent E. coli. These data reveal an important role of OMVs in bacterial defense mechanisms demonstrating that the OmpC and OmpF proteins allow permeation of β-lactam antibiotics into the lumen of OMVs, and antibiotics that enter the OMVs can be degraded by β-lactamase.

Role of outer membrane vesicles of bacteria

Resonance ◽  
2015 ◽  
Vol 20 (8) ◽  
pp. 711-725 ◽  
Author(s):  
M. V. Jagannadham ◽  
M. K. Chattopadhyay
Keyword(s):  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles

scholarly journals LPS Remodeling Triggers Formation of Outer Membrane Vesicles inSalmonella

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Wael Elhenawy ◽  
Michael Bording-Jorgensen ◽  
Ezequiel Valguarnera ◽  
M. Florencia Haurat ◽  
Eytan Wine ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Molecular Mechanisms ◽  
Lipid A ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Mass Spectrometry Analysis ◽  
Membrane Remodeling ◽  
Macrophage Infection ◽  
Spectrometry Analysis

ABSTRACTOuter membrane vesicles (OMV) are proposed to mediate multiple functions during pathogenesis and symbiosis. However, the mechanisms responsible for OMV formation remain poorly understood. It has been shown in eukaryotic membranes that lipids with an inverted-cone shape favor the formation of positive membrane curvatures. Based on these studies, we formulated the hypothesis that lipid A deacylation might impose shape modifications that result in the curvature of the outer membrane (OM) and subsequent OMV formation. We tested the effect of lipid A remodeling on OMV biogenesis employingSalmonella entericaserovar Typhimurium as a model organism. Expression of the lipid A deacylase PagL resulted in increased vesiculation, without inducing an envelope stress response. Mass spectrometry analysis revealed profound differences in the patterns of lipid A in OM and OMV, with accumulation of deacylated lipid A forms exclusively in OMV. OMV biogenesis by intracellular bacteria upon macrophage infection was drastically reduced in apagLmutant strain. We propose a novel mechanism for OMV biogenesis requiring lipid A deacylation in the context of a multifactorial process that involves the orchestrated remodeling of the outer membrane.IMPORTANCEThe role of lipid remodeling in vesiculation is well documented in eukaryotes. Similarly, bacteria produce membrane-derived vesicles; however, the molecular mechanisms underlying their production are yet to be determined. In this work, we investigated the role of outer membrane remodeling in OMV biogenesis inS. Typhimurium. We showed that the expression of the lipid A deacylase PagL results in overvesiculation with deacylated lipid A accumulation exclusively in OMV. AnS. Typhimurium ΔpagLstrain showed a significant reduction in intracellular OMV secretion relative to the wild-type strain. Our results suggest a novel mechanism for OMV biogenesis that involves outer membrane remodeling through lipid A modification. Understanding how OMV are produced by bacteria is important to advance our understanding of the host-pathogen interactions.

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