Fate of the fish pathogen <i>Aeromonas salmonicida</i> in the peritoneal cavity of rainbow trout

Garduño, Rafael A.; Thornton, Julian C.; Kay, William W.

doi:10.1139/m93-159

Cited by 43 publications

(41 citation statements)

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“…NO has a high affinity for haem and non-haem iron in prosthetic groups of proteins and must be internalized to carry out its deleterious effects (De Groote & Fang, 1995;Fang, 1997;Morris et al, 1995). Both Hms' and Hms-cells have a functional haemin transport system (Hornung et d., 1996) In A. salmonicida, haemin-binding by the A-layer increases the association of the bacteria with macrophages (Gardufio & Kay, 1992). Similarly, binding of haemin to S. flexneri enhances their uptake into HeLa cells and correlates with host cell invasion (Daskaleros & Payne, 1987;Stugard et aZ., 1989).…”

Section: Discussionmentioning

confidence: 99%

The haemin storage (Hms+) phenotype of Yersinia pestis is not essential for the pathogenesis of bubonic plague in mammals

LillardJr

Bearden²,

Fetherston³

et al. 1999

Microbiology

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The haemin storage (Hms+) phenotype of Yersinia pestis enables this bacillus to form greenish/brown or red colonies on haemin or Congo Red agar plates, respectively, at 26 but not 37 O C . Escherichia coli strains that contain mutations in genes essential for siderophore biosynthesis, porphyrin generation and/or haemin transport remain unable to utilize exogenous haemin as a nutritional iron or porphyrin source when transformed with the cloned Y. pestis hmsHFRS locus. Further physiological analysis of the Hms+ phenotype of Y. pestis strain KIM6+ suggests that the haemin and inorganic iron stored by the Hms system was not used nutritionally under subsequent iron-deficient conditions. In vitro analysis of the bactericidal effects of hydrogen peroxide, superoxide and nitric oxide showed that Hms' Y. pestis cells, in certain cases, were more susceptible than the Hms+ parent cells to these reactive oxygen species a t 26 and/or 37 "C.In adherence assays, a higher percentage of Hms+ cells were associated with HeLa cells and normal human neutrophils, compared to Hms' cells. However, the Hms+ phenotype did not provide any additional protection against the killing effects of neutrophils. Finally, LD, , analysis in subcutaneously infected mice showed that an Hms' strain was slightly more virulent than Hms+, indicating that the Hms phenotype is not essential for the pathogenesis of bubonic plague in mammals.

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Section: Discussionmentioning

confidence: 99%

The haemin storage (Hms+) phenotype of Yersinia pestis is not essential for the pathogenesis of bubonic plague in mammals

LillardJr

Bearden²,

Fetherston³

et al. 1999

Microbiology

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“…accumulate heme in their outer surface (21,34,42,62,105). Rather than a source of toxicity, this accumulation of heme is thought to contribute to bacterial pathogenesis by increasing bacterial heme storage, utilization, or host invasion (21,31,34,41,105). Moreover, iron-replete S. aureus preferentially traffics exogenously acquired heme to the cell membrane, although the function of this process is still unknown (94).…”

Section: Potential Mechanisms Of Heme Toxicitymentioning

confidence: 99%

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

2010

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Virtually all bacterial pathogens require iron to infect vertebrates. The most abundant source of iron within vertebrates is in the form of heme as a cofactor of hemoproteins. Many bacterial pathogens have elegant systems dedicated to the acquisition of heme from host hemoproteins. Once internalized, heme is either degraded to release free iron or used intact as a cofactor in catalases, cytochromes, and other bacterial hemoproteins. Paradoxically, the high redox potential of heme makes it a liability, as heme is toxic at high concentrations. Although a variety of mechanisms have been proposed to explain heme toxicity, the mechanisms by which heme kills bacteria are not well understood. Nonetheless, bacteria employ various strategies to protect against and eliminate heme toxicity. Factors involved in heme acquisition and detoxification have been found to contribute to virulence, underscoring the physiological relevance of heme stress during pathogenesis. Herein we describe the current understanding of the mechanisms of heme toxicity and how bacterial pathogens overcome the heme paradox during infection.

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“…However, only in a few instances have any functions of eubacterial S-layers been rigorously demonstrated, e.g., the protective role of S-layers against Bdellovibrio predation (34) or against nonspecific host defenses (5, 36) and the cell adhesion properties of the S-layer of the fish pathogenic bacterium Aeromonas salmonicida (16,17,43).…”

Section: ؉mentioning

confidence: 99%

“…Also, rough mutants of A. salmonicida lacking LPS O polysaccharide release either A-protein tetrameric units (22) or large sheets of arrayed layers (2,10) into the culture medium. Reattachment of these released S-layer materials to S Ϫ mutants has been demonstrated (16,22). Here, we report the specificity and requirements of the physical reconstitution process, which we have approached using different methods, as well as the functional characterization of the S-layer-reconstituted cells.…”

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confidence: 99%

Physical and functional S-layer reconstitution in Aeromonas salmonicida

1995

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The various functions attributed to the S-layer of Aeromonas salmonicida have been previously identified by their conspicuous absence in S-layer-defective mutants. As a different approach to establish the multifunctional nature of this S-layer, we established methods for reconstitution of the S-layer of A. salmonicida. Then we investigated the functional competence of the reconstituted S-layer. S-layers were reconstituted in different systems: on inert membranes or immobilized lipopolysaccharide (LPS) from purified S-layer protein (Aprotein) or on viable cells from either A-protein or preassembled S-layer sheets. In the absence of divalent cations and LPS, purified A-protein in solution spontaneously assembled into tetrameric oligomers and, upon concentration by ultrafiltration, into macroscopic, semicrystalline sheets formed by oligomers loosely organized in a tetragonal arrangement. In the presence of Ca 2؉, purified A-protein assembled into normal tetragonal arrays of interlocked subunits. A-protein bound with high affinity (K d , 1.55 ؋ 10 ؊7 M) and specificity to high-molecular-weight LPS from A. salmonicida but not to the LPSs of several other bacterial species. In vivo, A-protein could be reconstituted only on A. salmonicida cells which contained LPS, and Ca 2؉affected both a regular tetragonal organization of the reattached A-protein and an enhanced reattachment of the A-protein to the cell surface. The reconstitution of preformed S-layer sheets (produced by an S-layersecreting mutant) to an S-layer-negative mutant occurred consistently and efficiently when the two mutant strains were cocultured on calcium-replete solid media. Reattached A-protein (exposed on the surface of S-layer-negative mutants) was able to bind porphyrins and an S-layer-specific phage but largely lacked regular organization, as judged by its inability to bind immunoglobulins. Reattached S-layer sheets were regularly organized and imparted the properties of porphyrin binding, hydrophobicity, autoaggregation, adherence to and invasion of fish macrophages and epithelial cells, and resistance to macrophage cytotoxicity. However, cells with reconstituted S-layers were still sensitive to complement and insensitive to the antibiotics streptonigrin and chloramphenicol, indicating incomplete functional reconstitution.S-layers cover the cell surfaces of a wide range of bacteria and have been hypothesized to be involved in protection, molecular sieving, ion trapping, cell adhesion, surface recognition, and morphogenesis (35). However, only in a few instances have any functions of eubacterial S-layers been rigorously demonstrated, e.g., the protective role of S-layers against Bdellovibrio predation (34) or against nonspecific host defenses (5, 36) and the cell adhesion properties of the S-layer of the fish pathogenic bacterium Aeromonas salmonicida (16,17,43).The main cell surface antigenic determinants of A. salmonicida are a smooth layer of lipopolysaccharide (LPS), possessing O polysaccharides of homogeneous lengths, and an S-layer, composed...

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Fate of the fish pathogen Aeromonas salmonicida in the peritoneal cavity of rainbow trout

Cited by 43 publications

References 0 publications

The haemin storage (Hms+) phenotype of Yersinia pestis is not essential for the pathogenesis of bubonic plague in mammals

The haemin storage (Hms+) phenotype of Yersinia pestis is not essential for the pathogenesis of bubonic plague in mammals

Overcoming the Heme Paradox: Heme Toxicity and Tolerance in Bacterial Pathogens

Physical and functional S-layer reconstitution in Aeromonas salmonicida

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