Gram-Negative Bacteria Produce Membrane Vesicles Which Are Capable of Killing Other Bacteria

Abstract

Naturally produced membrane vesicles (MVs), isolated from 15 strains of gram-negative bacteria (Citrobacter,Enterobacter, Escherichia,Klebsiella, Morganella, Proteus,Salmonella, and Shigella strains), lysed many gram-positive (including Mycobacterium) and gram-negative cultures. Peptidoglycan zymograms suggested that MVs contained peptidoglycan hydrolases, and electron microscopy revealed that the murein sacculi were digested, confirming a previous modus operandi (J. L. Kadurugamuwa and T. J. Beveridge, J. Bacteriol. 174:2767–2774, 1996). MV-sensitive bacteria possessed A1α, A4α, A1γ, A2α, and A4γ peptidoglycan chemotypes, whereas A3α, A3β, A3γ, A4β, B1α, and B1β chemotypes were not affected. Pseudomonas aeruginosa PAO1 vesicles possessed the most lytic activity.

Interaction of Actinobacillus actinomycetemcomitans outer membrane vesicles with HL60 cells does not require leukotoxin

“…Bacterial MVs have been suggested to represent vehicles for the in vivo delivery of virulence factors to susceptible host cells (Grenier and Mayrand., 1987;Kadurugamuwa and Beveridge, 1995;Li et al, 1998;Kolling and Matthews, 1999) and our results support this hypothesis. The MVs secreted by A. actinomycetemcomitans rapidly interact with HL60 cells causing lysis.…”

“…Indeed, MVs have been previously shown to fuse with other bacterial membranes. Li et al (1998) showed that MVs from many bacterial species fuse with the outer membrane of recipient Gram-negative bacteria, resulting in the release of vesicle-encapsulated autolysins into the periplasm, causing lysis of the target organism. This was suggested to represent a predatory response that may function to allow microcolonies to thrive in a biofilm at the expense of neighboring cells Kadurugamuwa and Beveridge, 1999).…”

Bicyclic compounds repress membrane vesicle production andPseudomonasquinolone signal synthesis inPseudomonas aeruginosa

“…It is well known that MVs released by P. aeruginosa PAO1 possess high lytic activities and kill both Gram-negative and -positive bacteria because MVs contain peptidoglycan hydrolases (Li et al, 1998). Hence, it is believed that P. aeruginosa MVs are important to survive in microbial communities.…”

Membrane vesicles released byAvibacterium paragallinarumcontain putative virulence factors

“…Gram-negative bacteria produce membrane vesicles (MVs) during normal or stressing growth conditions (Kadurugamuwa & Beveridge, 1995;Beveridge, 1999). The release of these structures has been considered by several authors as a new secretion mechanism by which bacteria can damage host tissues because of virulence factors contained in or associated with MVs (Kadurugamuwa & Beveridge, 1997;Fiocca et al, 1999;Beveridge, 1999;Kato et al, 2002;Kesty et al, 2004), gain access to colonization tissues by killing other bacteria (Li et al, 1998), or can promote the adhesion of nonadherent bacteria favouring biofilm formation (Grenier & Belanger, 1991).…”