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Outer-inner membrane vesicles naturally secreted by gram-negative pathogenic bacteria.

Pérez-Cruz C, Delgado L, López-Iglesias C, Mercade E - PLoS ONE (2015)

Bottom Line: DNA and ATP, which are components solely found in the cell cytoplasm, were identified within membrane vesicles of these strains.The presence of DNA inside the O-IMVs produced by N. gonorrhoeae was confirmed by gold DNA immunolabeling with a specific monoclonal IgM against double-stranded DNA.A proteomic analysis of N. gonorrhoeae-derived membrane vesicles identified proteins from the cytoplasm and plasma membrane.

View Article: PubMed Central - PubMed

Affiliation: Laboratori de Microbiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.

ABSTRACT
Outer-inner membrane vesicles (O-IMVs) were recently described as a new type of membrane vesicle secreted by the Antarctic bacterium Shewanella vesiculosa M7T. Their formation is characterized by the protrusion of both outer and plasma membranes, which pulls cytoplasmic components into the vesicles. To demonstrate that this is not a singular phenomenon in a bacterium occurring in an extreme environment, the identification of O-IMVs in pathogenic bacteria was undertaken. With this aim, a structural study by Transmission Electron Microscopy (TEM) and Cryo-transmission electron microscopy (Cryo-TEM) was carried out, confirming that O-IMVs are also secreted by Gram-negative pathogenic bacteria such as Neisseria gonorrhoeae, Pseudomonas aeruginosa PAO1 and Acinetobacter baumannii AB41, in which they represent between 0.23% and 1.2% of total vesicles produced. DNA and ATP, which are components solely found in the cell cytoplasm, were identified within membrane vesicles of these strains. The presence of DNA inside the O-IMVs produced by N. gonorrhoeae was confirmed by gold DNA immunolabeling with a specific monoclonal IgM against double-stranded DNA. A proteomic analysis of N. gonorrhoeae-derived membrane vesicles identified proteins from the cytoplasm and plasma membrane. This confirmation of O-IMV extends the hitherto uniform definition of membrane vesicles in Gram-negative bacteria and explains the presence of components in membrane vesicles such as DNA, cytoplasmic and inner membrane proteins, as well as ATP, detected for the first time. The production of these O-IMVs by pathogenic Gram-negative bacteria opens up new areas of study related to their involvement in lateral gene transfer, the transfer of cytoplasmic proteins, as well as the functionality and role of ATP detected in these new vesicles.

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O-IMV visualized by TEM.TEM micrographs from HPF-FS sections of MVs isolated from (A) N. gonorrhoeae, (B) Pseudomonas PAO1 and (C) A. baumannii. O-IMVs observed in MV preparations from the three strains have certain features in common: all are surrounded by an external bilayer, probably corresponding to the outer membrane (OM) of the cell, and contain an inner membrane, probably corresponding to the plasma membrane (PM) of the cell, which entraps a high electron-dense material. In the image of O-IMVs from A. baumannii the putative peptidoglican layer (PG) can be seen. Bars 100 nm.
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pone.0116896.g003: O-IMV visualized by TEM.TEM micrographs from HPF-FS sections of MVs isolated from (A) N. gonorrhoeae, (B) Pseudomonas PAO1 and (C) A. baumannii. O-IMVs observed in MV preparations from the three strains have certain features in common: all are surrounded by an external bilayer, probably corresponding to the outer membrane (OM) of the cell, and contain an inner membrane, probably corresponding to the plasma membrane (PM) of the cell, which entraps a high electron-dense material. In the image of O-IMVs from A. baumannii the putative peptidoglican layer (PG) can be seen. Bars 100 nm.

Mentions: For the same purpose, MVs from the three strains grown on liquid cultures were isolated and analyzed by TEM after HPF-FS (Fig. 3). Although single-bilayer OMVs predominated in all observed fields, the new O-IMVs were detected in each of the three pathogenic bacteria, and presented a similar structure, which included a double bilayer surrounding highly electron-dense material.


Outer-inner membrane vesicles naturally secreted by gram-negative pathogenic bacteria.

Pérez-Cruz C, Delgado L, López-Iglesias C, Mercade E - PLoS ONE (2015)

O-IMV visualized by TEM.TEM micrographs from HPF-FS sections of MVs isolated from (A) N. gonorrhoeae, (B) Pseudomonas PAO1 and (C) A. baumannii. O-IMVs observed in MV preparations from the three strains have certain features in common: all are surrounded by an external bilayer, probably corresponding to the outer membrane (OM) of the cell, and contain an inner membrane, probably corresponding to the plasma membrane (PM) of the cell, which entraps a high electron-dense material. In the image of O-IMVs from A. baumannii the putative peptidoglican layer (PG) can be seen. Bars 100 nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4291224&req=5

pone.0116896.g003: O-IMV visualized by TEM.TEM micrographs from HPF-FS sections of MVs isolated from (A) N. gonorrhoeae, (B) Pseudomonas PAO1 and (C) A. baumannii. O-IMVs observed in MV preparations from the three strains have certain features in common: all are surrounded by an external bilayer, probably corresponding to the outer membrane (OM) of the cell, and contain an inner membrane, probably corresponding to the plasma membrane (PM) of the cell, which entraps a high electron-dense material. In the image of O-IMVs from A. baumannii the putative peptidoglican layer (PG) can be seen. Bars 100 nm.
Mentions: For the same purpose, MVs from the three strains grown on liquid cultures were isolated and analyzed by TEM after HPF-FS (Fig. 3). Although single-bilayer OMVs predominated in all observed fields, the new O-IMVs were detected in each of the three pathogenic bacteria, and presented a similar structure, which included a double bilayer surrounding highly electron-dense material.

Bottom Line: DNA and ATP, which are components solely found in the cell cytoplasm, were identified within membrane vesicles of these strains.The presence of DNA inside the O-IMVs produced by N. gonorrhoeae was confirmed by gold DNA immunolabeling with a specific monoclonal IgM against double-stranded DNA.A proteomic analysis of N. gonorrhoeae-derived membrane vesicles identified proteins from the cytoplasm and plasma membrane.

View Article: PubMed Central - PubMed

Affiliation: Laboratori de Microbiologia, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain.

ABSTRACT
Outer-inner membrane vesicles (O-IMVs) were recently described as a new type of membrane vesicle secreted by the Antarctic bacterium Shewanella vesiculosa M7T. Their formation is characterized by the protrusion of both outer and plasma membranes, which pulls cytoplasmic components into the vesicles. To demonstrate that this is not a singular phenomenon in a bacterium occurring in an extreme environment, the identification of O-IMVs in pathogenic bacteria was undertaken. With this aim, a structural study by Transmission Electron Microscopy (TEM) and Cryo-transmission electron microscopy (Cryo-TEM) was carried out, confirming that O-IMVs are also secreted by Gram-negative pathogenic bacteria such as Neisseria gonorrhoeae, Pseudomonas aeruginosa PAO1 and Acinetobacter baumannii AB41, in which they represent between 0.23% and 1.2% of total vesicles produced. DNA and ATP, which are components solely found in the cell cytoplasm, were identified within membrane vesicles of these strains. The presence of DNA inside the O-IMVs produced by N. gonorrhoeae was confirmed by gold DNA immunolabeling with a specific monoclonal IgM against double-stranded DNA. A proteomic analysis of N. gonorrhoeae-derived membrane vesicles identified proteins from the cytoplasm and plasma membrane. This confirmation of O-IMV extends the hitherto uniform definition of membrane vesicles in Gram-negative bacteria and explains the presence of components in membrane vesicles such as DNA, cytoplasmic and inner membrane proteins, as well as ATP, detected for the first time. The production of these O-IMVs by pathogenic Gram-negative bacteria opens up new areas of study related to their involvement in lateral gene transfer, the transfer of cytoplasmic proteins, as well as the functionality and role of ATP detected in these new vesicles.

Show MeSH
Related in: MedlinePlus