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Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

author:Fat Boy Research Society
Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Wen 丨 Fat Boy Research Society

Editor丨Fat Boy Research Society

preface

Whether from prokaryotes, eukaryotes, or archaea, most of the cells studied so far shed part of their outermost membrane containing biomolecules. Interestingly, the mechanisms driving vesicle production and release share many features in common in these three domains, emphasizing their importance for biological processes.

Bacterial membrane vesicles are the focus of this article and are called outer membrane vesicles (OMVs) or membrane vesicles (MVs), depending largely on whether they come from gram-negative bacteria or gram-positive bacteria, respectively.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Thereafter, the term "MVs" will be used to refer to two types of vesicles or vesicles specifically from gram-positive species, while "OMV" will specifically refer to vesicles from gram-negative bacteria with an outer membrane. Bacterial MVs are typically between 25-250 nm in diameter and contain proteins, lipids, nucleic acids, and other biomolecules of the parent bacteria.

Once seen as a product of cell debris or membrane regeneration, over the past few decades, researchers have shown that these biological nanoparticles have a greater role in cell function and community interactions.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

In the following chapters, this review will highlight recent findings and their role in bacterial membrane sacs in microbio-microbial interactions and interactions between microbial species and their host hosts.

Mediator of microbial community interactions

Much of the research in MV biology has focused on its function in pathogenesis; However, the important role of MV in microbial community interactions has also been identified and will be described in detail below.

Packaging goods into mvs enables them to perform special functions under changing or challenging environmental conditions, including quorum sensing (QS), biofilm formation, nutrient acquisition, antibiotic resistance, and competition or defense against other microorganisms. There is evidence that vesicles are not just a passive process, but rather act as a controlled mechanism for secretion of cellular or envelope components.

For example, in gram-negative bacteria, the outer membrane protein OmpA is necessary to maintain the link between the bacterial outer membrane and peptidoglycan, while lower levels of OmpA are associated with reduced membrane stability and increased vesicle action.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

In Vibrio cholerae, small RNA vrrA expression is upregulated under conditions that induce membrane stress and inhibits the translation of OmpA mRNA. This results in increased OMV release (inversely correlated with OmpA protein levels).

While the specific mechanisms involved are not yet fully detailed, the packaging of goods into vesicles appears to occur in the increased number of specific goods in the periplasm, as well as through the priority packaging method. The latter has been shown to be a condition of misfolding proteins that can selectively eliminate potentially toxic substances under stress conditions.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

In addition, selective cargo output under specific conditions and at specific functions outside the cell has also been demonstrated as it relates to community interactions between microorganisms.

The role of MV in QS and biofilm formation

Membrane vesicles play an important role in the propagation of QS signaling, enabling bacteria to communicate with each other and are important drivers of virulence in many pathogens. QS molecules of Pseudomonas aeruginosa (one of the main molecules signaling of Pseudomonas quinolones, mediating a variety of functions, including virulence factor production, regulation of host immune responses, cytotoxicity to competing microorganisms, and iron acquisition).

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Due to its chemical composition, PQS is highly hydrophobic, so it is unlikely to spread effectively in the environment. Conversely, studies have shown that about 86% of PQS is packaged as OMV.

Similarly, the hydrophobic QS molecule C16-HSL of Paracoccus denitrifying and the CAI-1 of Vibrio Harvey are packaged as vesicles, allowing for stabilization, concentration, and diffusion in the environment.

The QS mechanism can also affect OMV production, and PQS is necessary and sufficient for Pseudomonas aeruginosa, and can even induce MV formation in other gram-negative or even gram-positive species such as Escherichia coli, Burkholderia, and Bacillus subtilis.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

The mechanism of OMV biogenesis has been studied in detail and the interaction of PQS with lipid fractional lipopolysaccharides (lipopolysaccharides) proposed by the "bidual" model has found that the bacterial outer membrane causes the expansion of the outer flyer relative to the inner leaflet, causing the membrane to bend and eventually the small vesicles to be squeezed out. Other functions of QS signaling in MV biogenesis and content will be discussed later in the main disease interaction.

Membrane vesicles are important components of the bacterial biofilm matrix, including Pseudomonas aeruginosa, myxococcus, and Helicobacter pylori. Since bacterial biofilms are communities that may contain multiple different species, one species' contribution to the biofilm matrix may also benefit other species and enhance the overall function of biofilms in terms of cooperation, access to nutrients, and improved survival.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

In Pseudomonas aeruginosa, plankton and biofilm-derived OMVs differ in quantity and quality, they have proteolytic activity and antibiotic-binding capacity, suggesting that they are involved in some functions of biofilms.

Similar differences were observed in the size and size distribution of plankton and biofilm-derived MV viruses of Lactobacillus reuteri positive symbiosis, which may indicate functional differences with other members of the microbiome or human hosts.

DNA, which also acts as a matrix component of Pseudomonas aeruginosa biofilms, is specifically released in late logarithmic culture in response to QS signaling, which appears to occur at least in part by lysis of DNA-containing OMVs.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

In Helicobacter pylori, strain TK1402 has a strong biofilm-forming ability compared to other strains, which is highly correlated with the production of OMVs, and the addition of the OMV fraction of TK1402 can enhance the biofilm formation of another strain.

OMV from one organism may also promote adhesion in biofilms by another organism; For example, OMVs from the oral pathogen Porphyromonas gingivalis can enhance the aggregation and adhesion of multiple other oral microorganisms in plaque biofilms.

MV as a "public good" acquired by resources

In microbial communities, MVV released by one cell has the potential to provide benefits to other bacteria of the same or different species. For example, polysaccharide metabolism plays an important role in the establishment and composition of the human gut microbiota. There are several species in the genus Bacteroides, each with a different ability to utilize a variety of polysaccharides that reach the human colon intact.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

This depends on genes called polysaccharide utilization sites (PULs), which typically encode surface proteins that can bind, divide, or import specific polysaccharides and their lysates as well as further break down these products once they enter the cell, the proteins and regulatory proteins.

Proteomic analysis of OMVs with the outer membrane (OM) B. fragility and B. Taitao microparticles identify proteomes found only in OMV or OM, and OMV-specific proteomes are particularly rich in acidic lipoproteins with hydrolytic or carbohydrate-binding activity.

These OMVs are able to break down polysaccharides, and the resulting products can be consumed by all existing bacterial species, even those that do not produce the initial OMV.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

The enrichment of PUL-encoded hydrolases into OMVs indicates the presence of a mechanism that selectively packages certain proteins into OMVs for the purpose of being outside the cell rather than on the cell surface. Thus, glycoside hydrolases packaged as OMVs benefit the entire bacterial community as a "common good".

In the case of shared nutrient utilization based on the metabolic enzymes output in MV, are the nutrients using these MV sources purely utilized by recipient cells, or do they bring reciprocal benefits to MV producers. There is at least one known outer membrane vesicle of the Helicobacter pylori biofilm.

Transmission electron microscopy showing the formation and release of OMVs (arrows) during biofilm formation in bacteria-rich media. Reproduced with permission. Cooperative feeding strategies based on OMVs occur between Bacteroides ovale and Bacteroides vulgaris, two species that normally coexist at high density in the human gut.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Membrane vesicles can also facilitate nutrient access within microbial communities in other ways. They are vectors for gene transfer at the level of metabolic enzyme genes, just as cellulose in the rumen of the intestine degrades rumen cocci.

Klieve et al. determined linear, double-stranded DNA and hypothesized that chromosomal DNA was specifically processed into mV based on its small fragment size, the presence of repeated DNA sequences that may be used for packaging, and its resistance to restricted digestion (possibly due to modifications such as methylation), suggesting that DNA is intended for export extracellular.

The vesicles of wild-type birch can rescue mutants that cannot degrade crystalline cellulose, and the acquisition of this cellulose degradation is heritable, suggesting the role of vesicles in horizontal gene transfer of cellulose-degrading genes.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

While cellulose-degrading bacteria were previously known to produce MVs containing cellulose bodies, this report identifies for the first time DNA associated with birch vesicles, indicating MVs in addition to direct cellulose degradation. Further examples of horizontal gene transfer via OMV are discussed below.

There are multiple examples of MV functioning iron, which is key to bacterial growth, but is often limited in environments due to its poor solubility in water and the presence of oxygen and positive effects on the presence of oxygen by host organisms insulating it as an immune mechanism to slow the spread of pathogens.

For example, Mycobacterium tuberculosis increases vesicles under iron-limited conditions, and these MVs contain large amounts of mycobactin, an iron-chelating protein (siderophore).

Mycobactin is a hydrophobic molecule that accumulates in or near cell membranes and can then be efficiently incorporated into MV. Once released into the environment, these MVs can clear the available iron and then be sent back to bacterial cells, either the cells that originally produced the MV or their neighboring cells.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Sequestration of ferritin in MV may have a protective effect because in this state, ferritin is an iron-phore-repressor released by macrophages during the immune response.

MVs purified from cells grown in iron-restricted medium can restore the growth of mutant cells with insufficient siderophore biosynthesis, indicating that these MVs have a strong iron-clearing capacity, as well as their nature as a community resource.

Similarly, the Pseudomonas aeruginosa population-sensing molecule PQS is primarily exported to the surface of OMVs and can bind Fe3+ in the environment. The omv containing the PQS-Fe3+ complex is subsequently recaptured by TseF, a type 6 secretion system (T6SS) output protein that binds to PQS and interacts with sideroreceptor ligation on the cell surface.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

Like metabolic proteins, PQS is a hydrophobic molecule, and OMV provides a vehicle for protection and diffusion through the environment, as well as a mechanism for transporting essential elements through microbial populations.

Contrary to the evidence that MV is a public good that benefits the entire bacterial community, there is also evidence that MV interactions with bacterial cells may be selective. Omv from Enterobacter interacts with cells of the same or other Buttiella, while interacting with E. coli.

This may be due to the special physicochemical properties of cells and OMVs in these species, such as Brucella species. Compared to many other gram-negative bacteria (which produce less electrostatic repulsion between cells and OMV), and yeast that may facilitate specific OMV-cell interactions has significantly lower potential to recognize cell surface proteins.

Further research into this specificity of MV-cell interactions could lead to strategies for MV-based targeted cargo delivery to target bacterial cells.

Bacterial membrane vesicles act as mediators for microorganisms, microorganisms and microorganisms, host community interactions

The author's opinion

Membrane vesicles can also provide protective functions for microbial communities with harmful substances such as reactive oxygen species, antibiotics, antimicrobial peptides, and bacteriophages. In many cases, this again happens through MVs as "public goods". For example, in Helicobacter pylori, OMV is deployed as a protective mechanism against the release of reactive oxygen species from host immune cells (Figure 4).

Compared to the bacterial outer membrane, multiple strains of OMVs are selectively enriched in catalase KatA, which have greater hydrogen peroxide hydrolytic activity than whole cell lysates, thus protecting the surrounding environment from oxidative damage bacteria.

bibliography

Alves, New Jersey, Turner, Daniel, and Walper (2015). Bacterial nanobioreactors-guided enzyme packaging into bacterial outer membrane vesicles.

Bloomfield, G. and Kay (2016). Use and abuse of pinocytosis effect. J. Cell Science. 129, 2697–2705.

D., Hughes, Short and Roland, I. (2005). Potential mechanisms of probiotic anticancer effects

Dorward, D.W., Garon and Judd, R. C.(1989)。 DNA export and cell-to-cell transfer via Neisseria gonorrhoeae membrane vesicles.

Ernst, J.D. (2012). Immune life cycle of tuberculosis. Nat。 Rotational immunosuppressants of the engine.