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

Barua, Soumitra; Yamashino, Takafumi; Hasegawa, Tadao; Yokoyama, Keiko; Torii, Keizo; Ohta, Michio

doi:10.1046/j.1365-2958.2002.02768.x

Cited by 55 publications

(34 citation statements)

References 44 publications

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“…Compared with the long history of structure and function studies of other major bacterial surface glycolipids, such as LPS, definitive studies of ECA function are rare. Although a clear physiological role for the enterobacterial common antigen has not been determined, ECA has been linked to virulence in several species of bacteria (5,7,49,61). Despite this link to pathogenesis, the function of ECA seems to differ in each species.…”

Section: Discussionmentioning

confidence: 99%

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Enterobacterial Common Antigen Mutants of Salmonella enterica Serovar Typhimurium Establish a Persistent Infection and Provide Protection against Subsequent Lethal Challenge

et al. 2012

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Infection with Salmonella spp. is a significant source of disease globally. A substantial proportion of these infections are caused by Salmonella enterica serovar Typhimurium. Here, we characterize the role of the enterobacterial common antigen (ECA), a surface glycolipid ubiquitous among enteric bacteria, in S. Typhimurium pathogenesis. Construction of a defined mutation in the UDP-N-acetylglucosamine-1-phosphate transferase gene, wecA, in two clinically relevant strains of S. Typhimurium, TML and SL1344, resulted in strains that were unable to produce ECA. Loss of ECA did not affect the gross cell surface ultrastructure, production of lipopolysaccharide (LPS), flagella, or motility. However, the wecA mutant strains were attenuated in both oral and intraperitoneal mouse models of infection (P < 0.001 for both routes of infection; log rank test), and virulence could be restored by complementation of the wecA gene in trans. Despite the avirulence of the ECA-deficient strains, the wecA mutant strains were able to persistently colonize systemic sites (spleen and liver) at moderate levels for up to 70 days postinfection. Moreover, immunization with the wecA mutant strains provided protection against a subsequent lethal oral or intraperitoneal challenge with wild-type S. Typhimurium. Thus, wecA mutant (ECA-negative) strains of Salmonella may be useful as live attenuated vaccine strains or as vehicles for heterologous antigen expression. Salmonella enterica serovars are enteropathogens that display a broad range of host specificities and are common causes of gastroenteritis worldwide (47,48). In the United States alone, nontyphoidal Salmonella isolates cause an estimated 1.4 million cases of salmonellosis annually (12, 48), which results in up to $50 million per year in medical expenses and work absences (9). More than 2,500 different serotypes of Salmonella have been implicated in diarrheal disease (4, 12, 58); however, the majority of enteric salmonellosis cases are caused by a small subset of these serotypes (12,16,58), including Salmonella enterica serovar Typhimurium. Infection with S. Typhimurium can result in a debilitating inflammatory diarrhea that is often accompanied by fever, malaise, vomiting, muscle aches, and abdominal cramps (47).Salmonella serotypes that cause diarrheal disease are ingested in contaminated food and water and colonize the small intestine during passage through the digestive tract. Entry into the host intestinal tissue is thought to occur preferentially via antigensampling microfold (M) cells, although these pathogens can also invade enterocytes (28). Prior to M-cell entry, however, Salmonella must first survive/evade host defenses, such as the low pH of the stomach, bile salts, and various other innate immune mechanisms (16).A subset of the molecules that permit survival of bacteria in these initial steps in pathogenesis are located on the bacterial cell surface. The expression of these bacterial surface components has also been associated with virulence. Multiple reports have demonstr...

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Section: Discussionmentioning

confidence: 99%

“…To assess the bacterial loads at systemic sites, mice were inoculated with 1 ϫ 10 4 CFU of wild-type or wecAnull strains as indicated. Spleen and liver tissues were harvested at days 3,5,7,10,14,21,28,35,45,48,56,63, and 70 postinfection. Each tissue was homogenized, and an aliquot was serially diluted and plated to determine bacterial counts.…”

Section: Methodsmentioning

confidence: 99%

Enterobacterial Common Antigen Mutants of Salmonella enterica Serovar Typhimurium Establish a Persistent Infection and Provide Protection against Subsequent Lethal Challenge

et al. 2012

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“…Furthermore, the lateral diffusion of an OM protein, IcsA, becomes somewhat faster (perhaps twofold) in a mutant that cannot synthesize the LPS O chain (551). A recent report shows that deletion of the O side chain increases the weak-acid sensitivity of both E. coli and S. enterica serovar Typhimurium (38), but the effect is very slight. It should be noted that in most strains, only a small fraction of LPS molecules appear to contain long O side chains, a feature regulated by a gene called rol (reference 41 and references therein), cld, or wzz (537).…”

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confidence: 99%

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

Nikaido

2003

Microbiol Mol Biol Rev

3,840

3,800

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Gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. Although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. This review summarizes the development in the field since our previous review (H. Nikaido and M. Vaara, Microbiol. Rev. 49:1-32, 1985) was published. With the discovery of protein channels, structural knowledge enables us to understand in molecular detail how porins, specific channels, TonB-linked receptors, and other proteins function. We are now beginning to see how the export of large proteins occurs across the outer membrane. With our knowledge of the lipopolysaccharide-phospholipid asymmetric bilayer of the outer membrane, we are finally beginning to understand how this bilayer can retard the entry of lipophilic compounds, owing to our increasing knowledge about the chemistry of lipopolysaccharide from diverse organisms and the way in which lipopolysaccharide structure is modified by environmental conditions

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“…BMM305 shows increased sensitivity to mildly acidic pH. The absence of O antigen has been shown to increase the sensitivity of enteropathogenic E. coli to acid stress (6). The great majority of insects have hemolymph that is mildly acidic (38).…”

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confidence: 99%

ThepbgPEoperon inPhotorhabdus luminescensIs Required for Pathogenicity and Symbiosis

Bennett

Clarke

2005

J Bacteriol

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Photorhabdus is a genus of gram-negative Enterobacteriaceae that is pathogenic to insect larvae while also maintaining a mutualistic relationship with nematodes from the family Heterorhabditis, where the bacteria occupy the gut of the infective juvenile (IJ) stage of the nematode. In this study we describe the identification and characterization of a mutation in the pbgE1 gene of Photorhabdus luminescens TT01, predicted to be the fifth gene in the pbgPE operon. We show that this mutant, BMM305, is strongly attenuated in virulence against larvae of the greater wax moth, Galleria mellonella, and we report that BMM305 is more sensitive to the cationic antimicrobial peptide, polymyxin B, and growth in mildly acidic pH than the parental strain of P. luminescens. Moreover, we also show that the lipopolysaccharide (LPS) present on the surface of BMM305 does not appear to contain any O antigen. Complementation studies reveal that the increased sensitivity to polymyxin B and growth in mildly acidic pH can be rescued by the in trans expression of pbgE1, while the defects in O-antigen assembly and pathogenicity require the in trans expression of pbgE1 and the downstream genes pbgE2 and pbgE3. Finally, we show that BMM305 is defective in symbiosis as this mutant is unable to colonize the gut of the IJ stage of the nematode. Therefore, we conclude that the pbgPE operon is required for both pathogenicity and symbiosis in P. luminescens.Photorhabdus is a genus of gram-negative, bioluminescent insect pathogenic bacteria that also has a mutualistic relationship with entomophagous nematodes from the family Heterorhabditis (8). The bacteria colonize the gut of the infective juvenile (IJ) stage of the nematode, a free-living, infectious stage that lives in the soil and actively seeks out insect larvae. The IJ enters the larva and regurgitates the bacteria into the hemolymph, where the bacteria multiply and kill the insect within 24 to 48 h of infection. The bacteria also produce a wide range of extracellular hydrolytic enzymes that function to convert the internal organs and tissues of the insect into a nutrient soup that can support nematode growth and development. After two to three generations within the insect, the nematodes develop into IJs, the bacteria recolonize the intestinal tract, and the IJs emerge from the cadaver in search of a new host (for a recent review, see reference 19).It has been suggested that pathogenicity and symbiosis share common molecular mechanisms and that the outcome of a bacterium-host interaction is the result of a negotiation between the organisms involved in the interaction (28). The Photorhabdus-nematode-insect tripartite system provides a useful model system in which this question can be directly addressed. DNA sequencing has revealed that Photorhabdus contains many genes predicted to encode proteins with homology to virulence factors characterized in other bacterial pathogens (16,20). Recent work has identified the Tc toxin, a large protein complex that is orally active against insect larvae, a...

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

Cited by 55 publications

References 44 publications

Enterobacterial Common Antigen Mutants of Salmonella enterica Serovar Typhimurium Establish a Persistent Infection and Provide Protection against Subsequent Lethal Challenge

Enterobacterial Common Antigen Mutants of Salmonella enterica Serovar Typhimurium Establish a Persistent Infection and Provide Protection against Subsequent Lethal Challenge

Molecular Basis of Bacterial Outer Membrane Permeability Revisited

ThepbgPEoperon inPhotorhabdus luminescensIs Required for Pathogenicity and Symbiosis

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