Outer membrane-like vesicles secreted by Actinobacillus actinomycetemcomitans are enriched in leukotoxin

Kato, Soushi; Kowashi, Yusuke; Demuth, Donald R.

doi:10.1006/mpat.2001.0474

Cited by 234 publications

(240 citation statements)

References 49 publications

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“…actinomycetemcomitans LtxA is both secreted (18,19) and associated with the outer membrane of the cell (7,9,17,22). We show here that secretion of LtxA is required for hemolysis, since iron affects secretion but not ltxA synthesis.…”

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confidence: 70%

Regulation of Aggregatibacter ( Actinobacillus ) actinomycetemcomitans Leukotoxin Secretion by Iron

et al. 2006

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The gram-negative oral and systemic pathogen Aggregatibacter (Actinobacillus) actinomycetemcomitans produces a leukotoxin (LtxA) that is a member of the RTX (repeats in toxin) family of secreted bacterial toxins. We have recently shown that LtxA has the ability to lyse erythrocytes, which results in a beta-hemolytic phenotype on Columbia blood agar. To determine if LtxA is regulated by iron, we examined beta-hemolysis under iron-rich and iron-limiting conditions. Beta-hemolysis was suppressed in the presence of FeCl 3 . In contrast, strong beta-hemolysis occurred in the presence of the iron chelator deferoxamine. We found that secretion of LtxA was completely inhibited by free iron, but expression of ltxA was not regulated by iron. Free chromium, cobalt, and magnesium did not affect LtxA secretion. Other LtxA-associated genes were not regulated by iron. Thus, iron appears to play an important role in the regulation of LtxA secretion in A. actinomycetemcomitans in a manner independent of gene regulation.

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confidence: 70%

Regulation of Aggregatibacter ( Actinobacillus ) actinomycetemcomitans Leukotoxin Secretion by Iron

et al. 2006

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“…Many bacteria 28,29 , including E. coli 12 , are known to produce membrane vesicles that are involved in an intercellular transport of chemical signals 16 , lipids 30 , protein 31 , and DNA 12 , as well as in promoting adherence to other bacterial or eukaryotic host cells 32,33 . In most of these cases, membrane vesicles are believed to pinch off the producing cell and traverse the external environment as cell-independent units that eventually fuse with potential recipients 16 .…”

Section: Discussionmentioning

confidence: 99%

Metabolic cross-feeding via intercellular nanotubes among bacteria

et al. 2015

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Bacteria frequently exchange metabolites by diffusion through the extracellular environment, yet it remains generally unclear whether bacteria can also use cell-cell connections to directly exchange nutrients. Here we address this question by engineering cross-feeding interactions within and between Acinetobacter baylyi and Escherichia coli, in which two distant bacterial species reciprocally exchange essential amino acids. We establish that in a well-mixed environment E. coli, but likely not A. baylyi, can connect to other bacterial cells via membranederived nanotubes and use these to exchange cytoplasmic constituents. Intercellular connections are induced by auxotrophy-causing mutations and cease to establish when amino acids are externally supplied. Electron and fluorescence microscopy reveal a network of nanotubular structures that connects bacterial cells and enables an intercellular transfer of cytoplasmic materials. Together, our results demonstrate that bacteria can use nanotubes to exchange nutrients among connected cells and thus help to distribute metabolic functions within microbial communities.

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“…Other factors could contribute to the assembly of OM microdomains and therefore influence protein cargo selection. For example, it has been proposed that the lipid composition is different in OM and OMV (35,36). In addition, OM compartmentalization could be coupled to LPS and/or OM protein translocation processes (44).…”

Section: Discussionmentioning

confidence: 99%

Selective Sorting of Cargo Proteins into Bacterial Membrane Vesicles

Haurat¹,

Aduse‐Opoku

Rangarajan

et al. 2011

Journal of Biological Chemistry

272

290

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In contrast to the well established multiple cellular roles of membrane vesicles in eukaryotic cell biology, outer membrane vesicles (OMV) produced via blebbing of prokaryotic membranes have frequently been regarded as cell debris or microscopy artifacts. Increasingly, however, bacterial membrane vesicles are thought to play a role in microbial virulence, although it remains to be determined whether OMV result from a directed process or from passive disintegration of the outer membrane. Here we establish that the human oral pathogen Porphyromonas gingivalis has a mechanism to selectively sort proteins into OMV, resulting in the preferential packaging of virulence factors into OMV and the exclusion of abundant outer membrane proteins from the protein cargo. Furthermore, we show a critical role for lipopolysaccharide in directing this sorting mechanism. The existence of a process to package specific virulence factors into OMV may significantly alter our current understanding of host-pathogen interactions.

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Outer membrane-like vesicles secreted by Actinobacillus actinomycetemcomitans are enriched in leukotoxin

Cited by 234 publications

References 49 publications

Regulation of Aggregatibacter ( Actinobacillus ) actinomycetemcomitans Leukotoxin Secretion by Iron

Regulation of Aggregatibacter ( Actinobacillus ) actinomycetemcomitans Leukotoxin Secretion by Iron

Metabolic cross-feeding via intercellular nanotubes among bacteria

Selective Sorting of Cargo Proteins into Bacterial Membrane Vesicles

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