Production of Shiga toxin by Escherichia coli measured with reference to the membrane vesicle-associated toxins

Yokoyama, Kunihiro

doi:10.1016/s0378-1097(00)00424-9

Cited by 8 publications

(12 citation statements)

References 14 publications

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“…The MVs were confirmed as round projections on or around bacterial cells by immunoelectron microscopy (13,14,21). Extracellular toxins of Escherichia coli are produced during the exponential growth phase and are released into the growth medium as the MV form (28). In this study, many fragments were observed on the surface of F. psychrophilum.…”

Section: Discussionsupporting

confidence: 52%

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Changes in the Cell Structure of Flavobacterium psychrophilum with Length of Culture

Kondo

Kawai

Yagyu³

et al. 2001

Microbiology and Immunology

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Flavobacterium psychrophilum, the pathogen of bacterial cold-water disease, causes serious problems in ayu Plecoglossus altivelis culture. This study investigated the effect of the culture period of F. psychrophilum and on the structure of its cells, From the SDS-PAGE of total proteins of ceUular components, much difference was found between the 36 hr culture and the 48 and 72 hr cultures. A SEM observation of the cells showed many fragments, especially on the cell surface of the 36 hr culture. These fragments consisted of an outer membrane, seen by TEM observation, and may contain substances causing the virulence. Specific proteins observed by the SDS-PAGE and fragments in the 36 hr culture may be related to the virulence of F. psychrophilum.

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Section: Discussionsupporting

confidence: 52%

“…The virulence of bacteria often varies according to culture conditions, such as temperature, pH, NaCI concentration, nutritional substances, and culture age (6,12,19,24,28). Thus the culturing period is an important factor that may alter the virulence of pathogenic bacteria.…”

mentioning

confidence: 99%

Changes in the Cell Structure of Flavobacterium psychrophilum with Length of Culture

Kondo

Kawai

Yagyu³

et al. 2001

Microbiology and Immunology

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“…OM vesicles from Actinobacillus actinomycetemcomitans exhibit cytotoxicity (22,73,105), and Xenorhabdus nematophilus and Photorhabdus luminescens OM vesicles were cytotoxic for insect larvae as well as in tissue culture (79). Kolling and Matthews demonstrated, by immunoblotting, that Shiga toxin is present inside OM vesicles produced by O157:H7 cells (81), and this was corroborated for many strains of Shiga toxinproducing E. coli (STEC) under both aerobic and anaerobic conditions (143). NarE is a putatively vesicle-associated protein of Neisseria meningitidis vesicles that exhibits ADP-ribosyltransferase and NAD-glycohydrolase activities typically associated with toxicity (93).…”

Section: Vesicle-associated Toxinsmentioning

confidence: 96%

Virulence and Immunomodulatory Roles of Bacterial Outer Membrane Vesicles

Ellis

Kuehn

2010

Microbiol Mol Biol Rev

807

736

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SUMMARY Outer membrane (OM) vesicles are ubiquitously produced by Gram-negative bacteria during all stages of bacterial growth. OM vesicles are naturally secreted by both pathogenic and nonpathogenic bacteria. Strong experimental evidence exists to categorize OM vesicle production as a type of Gram-negative bacterial virulence factor. A growing body of data demonstrates an association of active virulence factors and toxins with vesicles, suggesting that they play a role in pathogenesis. One of the most popular and best-studied pathogenic functions for membrane vesicles is to serve as natural vehicles for the intercellular transport of virulence factors and other materials directly into host cells. The production of OM vesicles has been identified as an independent bacterial stress response pathway that is activated when bacteria encounter environmental stress, such as what might be experienced during the colonization of host tissues. Their detection in infected human tissues reinforces this theory. Various other virulence factors are also associated with OM vesicles, including adhesins and degradative enzymes. As a result, OM vesicles are heavily laden with pathogen-associated molecular patterns (PAMPs), virulence factors, and other OM components that can impact the course of infection by having toxigenic effects or by the activation of the innate immune response. However, infected hosts can also benefit from OM vesicle production by stimulating their ability to mount an effective defense. Vesicles display antigens and can elicit potent inflammatory and immune responses. In sum, OM vesicles are likely to play a significant role in the virulence of Gram-negative bacterial pathogens.

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“…The bacterial strains and plasmids used in this study are listed in Table 1. NGY9 was an isolate of the Sakai outbreak and the isolation of an isogenic rpoS ‐deficient mutant from NGY9 was performed as described previously (Yokoyama et al , 2000). All strains were stored at –80°C in 20% glycerol.…”

Section: Methodsmentioning

confidence: 99%

Involvement of surface polysaccharides in the organic acid resistance of Shiga Toxin‐producing Escherichia coli O157:H7

Barua

Yamashino

Hasegawa

et al. 2002

Molecular Microbiology

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Summary In general, wild Escherichia coli strains can grow effectively under moderately acidic organic acid‐rich conditions. We found that the Shiga Toxin‐producing E. coli (STEC) O157:H7 NGY9 grows more quickly than a K‐12 strain in Luria–Bertani (LB)‐2‐morpholinoethanesulphonic acid (MES) broth supplemented with acetic acid (pH 5.4). Hypothesizing that the resistance of STEC O157:H7 to acetic acid is as a result of a mechanism(s) other than those known, we screened for STEC mutants sensitive to acetic acid. NGY9 was subjected to mini‐Tn5 mutagenesis and, from 50 000 colonies, five mutants that showed a clear acetic acid‐sensitive phenotype were isolated. The insertion of mini‐Tn5 in three mutants occurred at the fcl, wecA (rfe) and wecB (rffE) genes and caused loss of surface O‐polysaccharide, loss of both O‐polysaccharide and enterobacterial common antigen (ECA) and loss of ECA respectively. The other two mutants showed inactivation of the waaG (rfaG) gene but at different positions that caused a deep rough mutant with loss of the outer core oligosaccharide of lipopolysaccharide (LPS) as well as phenotypic loss of O‐polysaccharide and ECA. With the introduction of plasmids carrying the fcl, wecA, wecB and waaG genes, respectively, all mutants were complemented in their production of O‐polysaccharide and ECA, and normal growth was restored in organic acid‐rich culture conditions. We also found that the growth of Salmonella LPS mutants Ra, Rb1, Rc, Rd1, Rd2 and Re was suppressed in the presence of acetic acid compared with that of the parents. These results suggest that the full expression of LPS (including O‐polysaccharide) and ECA is indispensable to the resistance against acetic acid and other short chain fatty acids in STEC O157:H7 and Salmonella. To the best of our knowledge, this is a newly identified physiological role for O‐polysaccharide and ECA as well as an acid resistance mechanism.

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Production of Shiga toxin by Escherichia coli measured with reference to the membrane vesicle-associated toxins

Cited by 8 publications

References 14 publications

Changes in the Cell Structure of Flavobacterium psychrophilum with Length of Culture

Changes in the Cell Structure of Flavobacterium psychrophilum with Length of Culture

Virulence and Immunomodulatory Roles of Bacterial Outer Membrane Vesicles

Involvement of surface polysaccharides in the organic acid resistance of Shiga Toxin‐producing Escherichia coli O157:H7

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