View source for Biology:Outer membrane vesicle

{{Short description|Vesicles released from the outer membranes of Gram-negative bacteria}}
[[File:Human_Salmonella_secreting_outer_membrane_vesicles_in_vivo_in_chicken_ileum_%28Original_work_of_Dr_R_C_YashRoy%29.png|thumb|right|300px|{{cuic|shrink=file|s=n|date=July 2017}} Transmission electron micrograph of outer membrane vesicles (OMV) (size 80–90 nm, dia) released by human pathogen ''Salmonella'' 3,10:r:- in chicken ileum, ''in vivo''. OMVs were proposed to be 'blown off' from large bacterial periplasmic protrusions, called ''periplasmic organelles'' (PO) with the help of 'bubble tube'-like assembly of about four type III secretion injectisomal ''rivet complexes'' (riveting bacterial outer and cell membrane to allow pockets of periplasm to expand into POs). This allows membrane vesicle trafficking of OMVs from gram negative bacteria to dock on host epithelial cell membrane (microvilli), proposed to translocate signal molecules from pathogen to host cells at the host–pathogen interface.]]

'''Outer membrane vesicles''' ('''OMVs''') are [[Biology:Vesicle (biology and chemistry)|vesicles]] released from the [[Biology:Bacterial outer membrane|outer membranes]] of [[Biology:Gram-negative bacteria|Gram-negative bacteria]]. While [[Biology:Gram-positive bacteria|Gram-positive bacteria]] release vesicles as well those vesicles fall under the broader category of bacterial membrane vesicles (MVs). OMVs were the first MVs to be discovered, and are distinguished from '''outer inner membrane vesicles''' (OIMVS), which are gram-negative baterial vesicles containing portions of both the outer and inner bacterial membrane.<ref>{{Cite journal|last1=Toyofuku|first1=Masanori|last2=Nomura|first2=Nobuhiko|last3=Eberl|first3=Leo|date=January 2019|title=Types and origins of bacterial membrane vesicles|journal=Nature Reviews Microbiology|volume=17|issue=1|pages=13–24|doi=10.1038/s41579-018-0112-2|pmid=30397270|s2cid=53224716 |issn=1740-1534}}</ref> Outer membrane vesicles were first discovered and characterized using [[Engineering:Transmission electron microscopy|transmission-electron microscopy]]<ref>{{Cite journal|last1=Chatterjee|first1=S. N.|last2=Das|first2=J.|date=1967|title=Electron microscopic observations on the excretion of cell-wall material by Vibrio cholerae|url=http://mic.sgmjournals.org/cgi/content/abstract/49/1/1|journal=Journal of General Microbiology|language=en|volume=49|issue=1|pages=1–11|issn=0022-1287|doi=10.1099/00221287-49-1-1|pmid=4168882|doi-access=}}</ref> by Indian Scientist Prof. Smriti Narayan Chatterjee and J. Das in 1966-67.<ref>{{Cite web|url=http://www.insaindia.res.in/detail/N86-0928|title=INSA :: Indian Fellow Detail|website=www.insaindia.res.in|access-date=2019-12-13}}</ref><ref>{{Cite journal|last1=Anand|first1=Deepak|last2=Chaudhuri|first2=Arunima|date=2016-11-16|title=Bacterial outer membrane vesicles: New insights and applications|journal=Molecular Membrane Biology|volume=33|issue=6–8|pages=125–137|doi=10.1080/09687688.2017.1400602|issn=0968-7688|pmid=29189113|doi-access=free}}</ref> OMVs are ascribed the functionality to provide a manner to communicate among themselves, with other [[Biology:Microorganism|microorganism]]s in their environment and with the host. These vesicles are involved in [[Biology:Membrane vesicle trafficking|trafficking]] bacterial [[Biology:Cell signaling|cell signaling]] biochemicals, which may include [[Biology:DNA|DNA]], [[Biology:RNA|RNA]], [[Biology:Proteins|proteins]], endotoxins and allied [[Biology:Virulence|virulence]] molecules. This communication happens in microbial cultures in oceans,<ref>Biller JJ, Schubotz F, Thompson AW, Summons RE and Chisholm SW (2014) Bacterial vesicles in marine ecosystems. ''Science'', vol. 343 (no. 6167), pp. 183–186. https://www.science.org/doi/abs/10.1126/science.1243457</ref> inside animals, plants and even inside the human body.<ref>{{cite journal |last1=Tulkens |first1=Joeri |last2=Vergauwen |first2=Glenn |last3=Van Deun |first3=Jan |last4=Geeurickx |first4=Edward |last5=Dhondt |first5=Bert |last6=Lippens |first6=Lien |last7=De Scheerder |first7=Marie-Angélique |last8=Miinalainen |first8=Ilkka |last9=Rappu |first9=Pekka |last10=De Geest |first10=Bruno G |last11=Vandecasteele |first11=Katrien |last12=Laukens |first12=Debby |last13=Vandekerckhove |first13=Linos |last14=Denys |first14=Hannelore |last15=Vandesompele |first15=Jo |last16=De Wever |first16=Olivier |last17=Hendrix |first17=An |title=Increased levels of systemic LPS-positive bacterial extracellular vesicles in patients with intestinal barrier dysfunction |journal=Gut |volume=69 |issue=1 |date=5 December 2018 |pages=gutjnl–2018–317726 |doi=10.1136/gutjnl-2018-317726|pmc=6943244 |pmid=30518529|doi-access=free }}</ref>

Gram-negative bacteria deploy their [[Biology:Periplasm|periplasm]] to secrete OMVs for trafficking bacterial biochemicals to target cells in their environment. OMVs also carry endotoxic [[Biology:Lipopolysaccharide|lipopolysaccharide]] initiating disease process in their host.<ref>YashRoy R C (1993) Electron microscope studies of surface pili and vesicles of ''Salmonella'' 3,10:r:- organisms. ''Indian Journal of Animal Sciences'', vol. 63 (no. 2), pp. 99–102. https://www.academia.edu/7327498/YashRoy_R_C_1993_Electron_microscope_studies_of_suraface_pili_and_vesicles_of_Salmonella_3_10_r_-_organisms.i_and_vesicles._Indian_Journal_of_Animal_Sciences._Vol_63_No.2_pp._99-102</ref> This mechanism imparts a variety of benefits like, long-distance delivery of bacterial secretory cargo with minimized hydrolytic degradation and extra-cellular dilution, also supplemented with other supportive molecules (e.g., virulence factors) to accomplish a specific job and yet, keeping a safe-distance from the defense arsenal of the targeted cells. Biochemical signals trafficked by OMVs may vary largely during 'war and peace' situations. In 'complacent' bacterial colonies, OMVs may be used to carry DNA to 'related' microbes for genetic transformations, and also translocate [[Biology:Cell signaling|cell signaling]] molecules for [[Biology:Quorum sensing|quorum sensing]] and [[Earth:Biofilm|biofilm]] formation. During 'challenge' from other cell types around, OMVs may be preferred to carry degradation and subversion enzymes. Likewise, OMVs may contain more of invasion proteins at the host–pathogen interface (Fig. 1). It is expected, that environmental factors around the secretory microbes are responsible for inducing these bacteria to synthesize and secrete specifically-enriched OMVs, physiologically suiting the immediate task. Thus, bacterial OMVs, being strong immunomodulators,<ref>Ellis TN and Kuehn MJ (2010) Virulence and immuno-modulatory roles of bacterial outer membrane vesicles. ''Microbiology and Molecular Biology Reviews'', vol. 74 (no. 1), pp. 81–94. http://mmbr.asm.org/content/74/1/81.short</ref> can be manipulated for their immunogenic contents and utilized as potent [[Biology:Pathogen|pathogen]]-free vaccines<ref>{{cite journal | last1 = Acevedo | first1 = R | last2 = Fernandez | first2 = S | last3 = Zayas | first3 = C | last4 = Acosta | first4 = D | last5 = Sarmiento | first5 = ME | last6 = Ferro | first6 = VA | last7 = Rosenquvist | first7 = E | last8 = Campa | first8 = C | last9 = Cardoso | first9 = D | last10 = Garcia | first10 = L | last11 = Perez | first11 = JL | year = 2014 | title = Bacterial outer membrane vesicles and vaccine applications | journal = Frontiers in Immunology | volume = 5 | page = 121 | pmc=3970029 | pmid=24715891 | doi=10.3389/fimmu.2014.00121| doi-access = free }}</ref> for immunizing humans and animals against threatening [[Medicine:Infection|infection]]s. [[Medicine:Meningococcal vaccine#Serogroup B|VA-MENGOC-BC and Bexsero]] against [[Medicine:Meningitis|meningitis]] are currently the only OMV vaccines approved in the US, though an OMV vaccine for [[Medicine:Gonorrhea|gonorrhea]] is seeking approval.<ref>{{cite journal |last1=Lieberman|first1=Linda|date=21 December 2022|title=Outer membrane vesicles: A bacterial-derived vaccination system|journal= Frontiers in Microbiology|volume= 13|issue= |pages= |doi=10.3389/fmicb.2022.1029146|pmid=36620013 |pmc=9811673 |doi-access=free }}</ref><ref>{{cite news |last= |first= |date=27 June 2023|title=GSK's gonorrhoea vaccine receives FDA's 'fast-track' designation|url=https://www.reuters.com/business/healthcare-pharmaceuticals/gsks-gonorrhoea-vaccine-receives-fdas-fast-track-designation-2023-06-27/|work={{wipe|Reuters}}|location= |access-date=20 August 2023}}</ref> 

==Biogenesis and movement==
Gram-negative bacteria have a double set of [[Biology:Lipid bilayer|bilayers]]. An inner bilayer, the inner [[Biology:Cell membrane|cell membrane]], encloses the [[Biology:Cytoplasm|cytoplasm]] or [[Biology:Cytosol|cytosol]]. Surrounding this inner cell membrane there is a second bilayer called the [[Biology:Bacterial outer membrane|bacterial outer membrane]]. The compartment or space between these two membranes is called the [[Biology:Periplasm|periplasm]] or periplasmic space. In addition, there is a firm [[Biology:Cell wall|cell wall]] consisting of [[Biology:Peptidoglycan|peptidoglycan]] layer, which surrounds the cell membrane and occupies the periplasmic space. The peptidoglycan layer provides some rigidity for maintaining the bacterial cell shape, besides also protecting the microbe against challenging environments.

The first step in [[Biology:Biogenesis|biogenesis]] of gram-negative bacterial OMVs,<ref>{{cite journal | last1 = Kulp | first1 = A | last2 = Kuehn | first2 = MJ | year = 2010 | title = Biological functions and biogenesis of secreted bacterial outer membrane vesicles | journal = Annual Review of Microbiology | volume = 64 | pages = 163–184 | pmc=3525469 | pmid=20825345 | doi=10.1146/annurev.micro.091208.073413}}</ref> is ''bulging'' of outer membrane above the peptidoglycan layer. Accumulation of phospholipids in the outside of the outer membrane is thought to be the basis of this outwards bulging of the outer membrane.<ref name=":0">{{Cite journal|last1=Roier|first1=Sandro|last2=Zingl|first2=Franz G.|last3=Cakar|first3=Fatih|last4=Durakovic|first4=Sanel|last5=Kohl|first5=Paul|last6=Eichmann|first6=Thomas O.|last7=Klug|first7=Lisa|last8=Gadermaier|first8=Bernhard|last9=Weinzerl|first9=Katharina|last10=Prassl|first10=Ruth|last11=Lass|first11=Achim|date=2016-01-25|title=A novel mechanism for the biogenesis of outer membrane vesicles in Gram-negative bacteria|journal=Nature Communications|language=en|volume=7|issue=1|pages=10515|doi=10.1038/ncomms10515|pmid=26806181|pmc=4737802|issn=2041-1723|bibcode=2016NatCo...710515R}}</ref> This accumulation of phospholipids can be regulated by the VacJ/Yrb ABC transport system that transfers phospholipids from the outside of OM to the inner side.<ref name=":0" /> Additionally, environmental conditions as sulfur depletion can trigger a state of phospholipid overproduction that causes increased OMV release.<ref>{{Cite journal|last1=Gerritzen|first1=Matthias J. H.|last2=Martens|first2=Dirk E.|last3=Uittenbogaard|first3=Joost P.|last4=Wijffels|first4=René H.|last5=Stork|first5=Michiel|date=2019-03-18|title=Sulfate depletion triggers overproduction of phospholipids and the release of outer membrane vesicles by Neisseria meningitidis|journal=Scientific Reports|language=en|volume=9|issue=1|pages=4716|doi=10.1038/s41598-019-41233-x|pmid=30886228|pmc=6423031|issn=2045-2322|bibcode=2019NatSR...9.4716G}}</ref>

The actual release of the vesicle from the outer membrane remains unclear. It is likely that vesicle structures can be released spontaneously. Alternatively, it has been suggested that few proteins 'rivet' the outer and cell membranes together, so that the periplasmic bulge protrudes like a 'ballooned' pocket of inflated periplasm out from the surface of the outer membrane. Lateral diffusion of 'rivet complexes' may help in pinching off large bulges of periplasm as OMVs.<ref>YashRoy R C (2003) Eucaryotic cell intoxication by Gram-negative organisms: A novel bacterial outermembrane-bound nanovesicular model for Type-III secretion system. ''Toxicology International'', vol. 10 (No. 1), 1-9.https://www.academia.edu/7695646/YashRoy_R_C_2003_Eukaryotic_cell_intoxication_by_Gram-negative_pathogens_A_novel_bacterial_outer_membrane-bound_nanovesicular_exocytosis_model_for_Type-III_secretion_system._Toxicology_International._Vol._10_No._1_pp._1-9</ref>

Bacterial membrane vesicles dispersion along the cell surface was measured in live ''[[Biology:Escherichia coli|Escherichia coli]]'', commensal bacteria common in the human gut. Antibiotic treatment altered vesicle dynamics, vesicle-to-membrane affinity, and surface properties of the cell membranes, generally enhancing vesicle transport along the surfaces of bacterial membranes and suggesting that their motion properties could be a signature of antibiotic stress.<ref name="Bos2021">{{cite journal | vauthors = Bos J, Cisneros LH, Mazel D | title = Real-time tracking of bacterial membrane vesicles reveals enhanced membrane traffic upon antibiotic exposure | journal = Science Advances | volume = 7 | issue = 4 | date = January 2021 | pages = eabd1033 | doi = 10.1126/sciadv.abd1033| pmid = 33523924 |pmc=7817102 }}</ref> Despite this first high-resolution, quantitative tracking of bacterial OMVs, detailed experimental work is still awaited to understand the [[Biology:Biomechanics|biomechanics]] of OMV biogenesis and transport. OMVs are also under focus of current research in [[Biology:Exocytosis|exocytosis]] in prokaryotes via outer [[Biology:Membrane vesicle trafficking|membrane vesicle trafficking]] for intra-species, inter-species and inter-kingdom [[Biology:Cell signaling|cell signaling]], which is slated to change our mindset on [[Biology:Virulence|virulence]] of microbes, [[Biology:Host–pathogen interaction|host–pathogen interaction]]s and inter-relationships among variety of species in earth's [[Earth:Ecosystem|ecosystem]].

==See also==
* [[Biology:Exocytosis|Exocytosis]]
* [[Biology:Host–pathogen interaction|Host–pathogen interaction]]s
* Host–pathogen interface
* [[Biology:List of bacterial disulfide oxidoreductases|List of bacterial disulfide oxidoreductases]]
* [[Biology:Virulence|Virulence]]

==References==
{{reflist}}

[[Category:Bacteriology]]
[[Category:Membrane biology]]

{{Sourceattribution|Outer membrane vesicle}}