Superoxide Dismutase Is a Virulence Factor Produced by the Coral Bleaching Pathogen Vibrio shiloi

Virulence, as determined in a mouse model, and virulence factor activities of catalase (CA), superoxide dismutase (SOD) and listeriolysin O (LLO), was examined in Listeria monocytogenes 10403S. Cells were propagated in media containing various concentrations of sodium chloride (NaCl) at 4, 25 and 37°C. Strain 10403S exhibited significant increases in CA activity and LLO when grown in media containing 428 mM of NaCl at 37°C. The CA activities at 4 and 25°C were significantly less, and the cells exhibited similar increases and decreases as cells grown at 37°C. When comparing the growth temperatures, the CA activity decreased as the growth temperature decreased. The SOD activity was significantly increased only when cells were propagated in media containing either 428 or 1,112 mM of NaCl. The SOD activity increased as the growth temperature decreased. No LLO activity was detected when cells were grown at 4 and 25°C. The production of these enzymes appeared to be thermoregulated. In addition, approximate lethal dose (ALD50) values were determined after intragastric (i.g.) and intraperitoneal (i.p.) infection. Each method of infection indicated that LLO was required for virulence, while growth in salt containing media, growth at 4°C, or the production of higher levels of CA, SOD and LLO did not appear to influence the virulence of L. monocytogenes.

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The marine fireworm Hermodice carunculata is a winter reservoir and spring-summer vector for the coral-bleaching pathogen Vibrio shiloi

Environmental Microbiology ◽

10.1046/j.1462-2920.2003.00424.x ◽

2003 ◽

Vol 5 (4) ◽

pp. 250-255 ◽

Cited By ~ 105

Author(s):

Meir Sussman ◽

Yossi Loya ◽

Maoz Fine ◽

Eugene Rosenberg

Keyword(s):

Coral Bleaching ◽

Hermodice Carunculata ◽

Vibrio Shiloi

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Random T-DNA Mutagenesis Identifies a Cu/Zn Superoxide Dismutase Gene as a Virulence Factor of Sclerotinia sclerotiorum

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-07-12-0177-r ◽

2013 ◽

Vol 26 (4) ◽

pp. 431-441 ◽

Cited By ~ 29

Author(s):

Liangsheng Xu ◽

Weidong Chen

Keyword(s):

Oxidative Stress ◽

Growth Rate ◽

Superoxide Dismutase ◽

Sclerotinia Sclerotiorum ◽

Virulence Factor ◽

Wild Type ◽

Expression Levels ◽

Sclerotial Formation ◽

Increased Sensitivity ◽

And Oxidative Stress

Agrobacterium-mediated transformation (AMT) was used to identify potential virulence factors in Sclerotinia sclerotiorum. Screening AMT transformants identified two mutants showing significantly reduced virulence. The mutants showed growth rate, sclerotial formation, and oxalate production similar to that of the wild type. The mutation was due to a single T-DNA insertion at 212 bp downstream of the Cu/Zn superoxide dismutase (SOD) gene (SsSOD1, SS1G_00699). Expression levels of SsSOD1 were significantly increased under oxidative stresses or during plant infection in the wild-type strain but could not be detected in the mutant. SsSOD1 functionally complemented the Cu/Zn SOD gene in a Δsod1 Saccharomyces cerevisiae mutant. The SOD mutant had increased sensitivity to heavy metal toxicity and oxidative stress in culture and reduced ability to detoxify superoxide in infected leaves. The mutant also had reduced expression levels of other known pathogenicity genes such as endo-polygalacturanases sspg1 and sspg3. The functions of SsSOD1 were further confirmed by SsSOD1-deletion mutation. Like the AMT insertion mutant, the SsSOD1-deletion mutant exhibited normal growth rate, sclerotial formation, oxalate production, increased sensitivity to metal and oxidative stress, and reduced virulence. These results suggest that SsSOD1, while not being required for saprophytic growth and completion of the life cycle, plays critical roles in detoxification of reactive oxygen species during host–pathogen interactions and is an important virulence factor of Sclerotinia sclerotiorum.

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Penetration of the Coral-Bleaching BacteriumVibrio shiloi into Oculina patagonica

Applied and Environmental Microbiology ◽

10.1128/aem.66.7.3031-3036.2000 ◽

2000 ◽

Vol 66 (7) ◽

pp. 3031-3036 ◽

Cited By ~ 83

Author(s):

E. Banin ◽

T. Israely ◽

A. Kushmaro ◽

Y. Loya ◽

E. Orr ◽

...

Keyword(s):

Coral Bleaching ◽

Agar Medium ◽

Viable Count ◽

Coral Tissue ◽

Intracellular Bacteria ◽

Initial Inoculum ◽

A Value ◽

Vibrio Shiloi ◽

High Concentrations

ABSTRACT Inoculation of the coral-bleaching bacterium Vibrio shiloi into seawater containing its host Oculina patagonica led to adhesion of the bacteria to the coral surface via a β-d-galactose receptor, followed by penetration of the bacteria into the coral tissue. The internalized V. shiloi cells were observed inside the exodermal layer of the coral by electron microscopy and fluorescence microscopy using specific anti-V. shiloi antibodies to stain the intracellular bacteria. At 29Ã¯Â¿Â½C, 80% of the bacteria bound to the coral within 8 h. Penetration, measured by the viable count (gentamicin invasion assay) inside the coral tissue, was 5.6, 20.9, and 21.7% of the initial inoculum at 8, 12, and 24 h, respectively. The viable count in the coral tissue decreased to 5.3% at 48 h, and none could be detected at 72 h. Determination of V. shiloi total counts (using the anti-V. shiloiantibodies) in the coral tissue showed results similar to viable counts for the first 12 h of infection. After 12 h, however, the total count more than doubled from 12 to 24 h and continued to rise, reaching a value 6 times that of the initial inoculum at 72 h. Thus, the intracellular V. shiloi organisms were transformed into a form that could multiply inside the coral tissue but did not form colonies on agar medium. Internalization of the bacteria was accompanied by the production of high concentrations of V. shiloi toxin P activity in the coral tissue. Internalization and multiplication of V. shiloi are discussed in terms of the mechanism of bacterial bleaching of corals.

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RNA-Mediated Gene Silencing of Superoxide Dismutase (bcsod1) in Botrytis cinerea

Phytopathology ◽

10.1094/phyto-98-12-1334 ◽

2008 ◽

Vol 98 (12) ◽

pp. 1334-1339 ◽

Cited By ~ 29

Author(s):

R. M. Patel ◽

J. A. L. van Kan ◽

A. M. Bailey ◽

G. D. Foster

Keyword(s):

Superoxide Dismutase ◽

Gene Silencing ◽

Botrytis Cinerea ◽

Virulence Factor ◽

High Throughput ◽

Gene Function ◽

In Planta

Gene silencing is a powerful tool utilized for identification of gene function and analysis in plants, animals, and fungi. Here, we report the silencing of superoxide dismutase (bcsod1) in Botrytis cinerea through sense and antisense-mediated silencing mechanisms. Because superoxide dismutase (SOD) is a virulence factor, transformants were tested for phenotypic silencing in vitro and reduction in pathogenicity in planta. Plate-based assays with and without paraquat were performed to screen initial silencing efficiency, and a subset of transformants was used for in planta studies of virulence. Transformants exhibiting strongly decreased transcripts levels were recovered with both constructs but none of those exhibited a reduction in virulence in planta. Our investigations may help optimize a high-throughput gene silencing system useful for identifying potential gene targets for future fungal control.

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Genome analysis of the coral bleaching pathogen Vibrio shiloi

Archives of Microbiology ◽

10.1007/s00203-008-0388-0 ◽

2008 ◽

Vol 190 (2) ◽

pp. 185-194 ◽

Cited By ~ 15

Author(s):

Leah Reshef ◽

Eliora Ron ◽

Eugene Rosenberg

Keyword(s):

Coral Bleaching ◽

Genome Analysis ◽

Vibrio Shiloi

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Proline-Rich Peptide from the Coral PathogenVibrio shiloi That Inhibits Photosynthesis of Zooxanthellae

Applied and Environmental Microbiology ◽

10.1128/aem.67.4.1536-1541.2001 ◽

2001 ◽

Vol 67 (4) ◽

pp. 1536-1541 ◽

Cited By ~ 63

Author(s):

Ehud Banin ◽

Sanjay K. Khare ◽

Fred Naider ◽

Eugene Rosenberg

Keyword(s):

Molecular Weight ◽

Coral Bleaching ◽

Rapid Decrease ◽

Bulk Liquid ◽

Symbiotic Algae ◽

P Concentration ◽

Vibrio Shiloi ◽

Casamino Acids ◽

Proline Rich Peptide ◽

Subsequent Addition

ABSTRACT The coral-bleaching bacterium Vibrio shiloibiosynthesizes and secretes an extracellular peptide, referred to as toxin P, which inhibits photosynthesis of coral symbiotic algae (zooxanthellae). Toxin P was produced during the stationary phase when the bacterium was grown on peptone or Casamino Acids media at 29°C. Glycerol inhibited the production of toxin P. Toxin P was purified to homogeneity, yielding the following 12-residue peptide: PYPVYAPPPVVP (molecular weight, 1,295.54). The structure of toxin P was confirmed by chemical synthesis. In the presence of 12.5 mM NH4Cl, pure natural or synthetic toxin P (10 μM) caused a 64% decrease in the photosynthetic quantum yield of zooxanthellae within 5 min. The inhibition was proportional to the toxin P concentration. Toxin P bound avidly to zooxanthellae, such that subsequent addition of NH4Cl resulted in rapid inhibition of photosynthesis. When zooxanthellae were incubated in the presence of NH4Cl and toxin P, there was a rapid decrease in the pH (pH 7.8 to 7.2) of the bulk liquid, suggesting that toxin P facilitates transport of NH3 into the cell. It is known that uptake of NH3 into cells can destroy the pH gradient and block photosynthesis. This mode of action of toxin P can help explain the mechanism of coral bleaching by V. shiloi.

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Superoxide Dismutase-Deficient Mutants ofHelicobacter pylori Are Hypersensitive to Oxidative Stress and Defective in Host Colonization

Infection and Immunity ◽

10.1128/iai.69.6.4034-4040.2001 ◽

2001 ◽

Vol 69 (6) ◽

pp. 4034-4040 ◽

Cited By ~ 113

Author(s):

Richard W. Seyler ◽

Jonathan W. Olson ◽

Robert J. Maier

Keyword(s):

Oxidative Stress ◽

Superoxide Dismutase ◽

Virulence Factor ◽

Type Strain ◽

Wild Type Strain ◽

Spontaneous Mutation ◽

Wild Type ◽

Sod Activity ◽

Cell Extracts ◽

H Pylori

ABSTRACT Superoxide dismutase (SOD) is a nearly ubiquitous enzyme among organisms that are exposed to oxic environments. The single SOD ofHelicobacter pylori, encoded by the sodB gene, has been suspected to be a virulence factor for this pathogenic microaerophile, but mutations in this gene have not been reported previously. We have isolated mutants with interruptions in thesodB gene and have characterized them with respect to their response to oxidative stress and ability to colonize the mouse stomach. The sodB mutants are devoid of SOD activity, based on activity staining in nondenaturing gels and quantitative assays of cell extracts. Though wild-type H. pylori is microaerophilic, the mutants are even more sensitive to O2 for both growth and viability. While the wild-type strain is routinely grown at 12% O2, growth of the mutant strains is severely inhibited at above 5 to 6% O2. The effect of O2 on viability was determined by subjecting nongrowing cells to atmospheric levels of O2 and plating for survivors at 2-h time intervals. Wild-type cell viability dropped by about 1 order of magnitude after 6 h, while viability of the sodBmutant decreased by more than 6 orders of magnitude at the same time point. The mutants are also more sensitive to H2O2, and this sensitivity is exacerbated by increased O2 concentrations. Since oxidative stress has been correlated with DNA damage, the frequency of spontaneous mutation to rifampin resistance was studied. The frequency of mutagenesis of ansodB mutant strain is about 15-fold greater than that of the wild-type strain. In the mouse colonization model, only 1 out of 23 mice inoculated with an SOD-deficient mutant of a mouse-adapted strain became H. pylori positive, while 15 out of 17 mice inoculated with the wild-type strain were shown to harbor the organism. Therefore, SOD is a virulence factor which affects the ability of this organism to colonize the mouse stomach and is important for the growth and survival of H. pylori under conditions of oxidative stress.

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