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Cupric yersiniabactin is a virulence-associated superoxide dismutase mimic.

Chaturvedi KS, Hung CS, Giblin DE, Urushidani S, Austin AM, Dinauer MC, Henderson JP - ACS Chem. Biol. (2013)

Bottom Line: Among these, the virulence-associated siderophore yersiniabactin (Ybt) is an avid copper chelator, forming stable cupric (Cu(II)-Ybt) complexes that are detectable in infected patients.Unlike previously described synthetic copper-salicylate (Cu(II)-SA) SOD mimics, the salicylate-based natural product Cu(II)-Ybt retains catalytic activity at physiologically plausible protein concentrations.These results reveal a new virulence-associated adaptation based upon spontaneous assembly of a non-protein catalyst.

View Article: PubMed Central - PubMed

Affiliation: Center for Women's Infectious Diseases Research, ‡Division of Infectious Diseases, §Department of Internal Medicine, ∥Department of Chemistry, ⊥Department of Pediatrics, and #Department of Pathology and Immunology, Washington University School of Medicine , St. Louis, Missouri 63110, United States.

ABSTRACT
Many Gram-negative bacteria interact with extracellular metal ions by expressing one or more siderophore types. Among these, the virulence-associated siderophore yersiniabactin (Ybt) is an avid copper chelator, forming stable cupric (Cu(II)-Ybt) complexes that are detectable in infected patients. Here we show that Ybt-expressing E. coli are protected from intracellular killing within copper-replete phagocytic cells. This survival advantage is highly dependent upon the phagocyte respiratory burst, during which superoxide is generated by the NADPH oxidase complex. Chemical fractionation links this phenotype to a previously unappreciated superoxide dismutase (SOD)-like activity of Cu(II)-Ybt. Unlike previously described synthetic copper-salicylate (Cu(II)-SA) SOD mimics, the salicylate-based natural product Cu(II)-Ybt retains catalytic activity at physiologically plausible protein concentrations. These results reveal a new virulence-associated adaptation based upon spontaneous assembly of a non-protein catalyst.

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Cu(II)-Ybtis a superoxide dismutase mimic. Superoxide’sinteraction with Cu(II)-Ybt was probed in vitro withthe superoxide-generating xanthine/xanthine oxidase (XO) reactionsystem. (a) A dose–response relationship is observed betweenCu(II)-Ybt and SOD activity. (b) Cu(II)-Ybt concentrations remainunchanged following exposure to the intact xanthine/xanthine oxidasesystem. (c) In a complete reaction system, 10 μM Cu(II)-Ybtgenerates 0.04 μM hydrogen peroxide (H2O2) in the presence of superoxide anion, which is significantly (p = 0.0067, Mest) higher than the H2O2 generated in the presence of apo-Ybt alone or the negative control.(d) SOD ctivify is negligible for apo-Ybt alone but 63.12% and 41.4%for its Cu(II) andFe(III) complexes, respectively. This activity isabsent in complexes with the redox-inactive metal Ga(III). Resultsare reported as a normalized percentage compared to positive controlstreated with bovine superoxide dismutase. The data are presented asmeans ± SD of five independent experiments.
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fig4: Cu(II)-Ybtis a superoxide dismutase mimic. Superoxide’sinteraction with Cu(II)-Ybt was probed in vitro withthe superoxide-generating xanthine/xanthine oxidase (XO) reactionsystem. (a) A dose–response relationship is observed betweenCu(II)-Ybt and SOD activity. (b) Cu(II)-Ybt concentrations remainunchanged following exposure to the intact xanthine/xanthine oxidasesystem. (c) In a complete reaction system, 10 μM Cu(II)-Ybtgenerates 0.04 μM hydrogen peroxide (H2O2) in the presence of superoxide anion, which is significantly (p = 0.0067, Mest) higher than the H2O2 generated in the presence of apo-Ybt alone or the negative control.(d) SOD ctivify is negligible for apo-Ybt alone but 63.12% and 41.4%for its Cu(II) andFe(III) complexes, respectively. This activity isabsent in complexes with the redox-inactive metal Ga(III). Resultsare reported as a normalized percentage compared to positive controlstreated with bovine superoxide dismutase. The data are presented asmeans ± SD of five independent experiments.

Mentions: To determine the origin of SOD-likeactivity in copper-repletewild-type supernatants, we analyzed fractions by liquid chromatography–massspectrometry (LC–MS). The LC–MS chromatogram from the80% fraction was dominated by a single peak corresponding to Cu(II)-Ybt(Figure 3c). A preparation of purified Cu(II)-Ybtsimilarly exhibited SOD-like activity with a dose–responserelationship (Figure.4a). For 0.12, 0.6, 3.0,and 15.0 mM solutions of Cu(II)-Ybt, the percentage inhibition rateswere determined to be 4.6%, 19.8%, 24.3%, and 55.7%, respectively.


Cupric yersiniabactin is a virulence-associated superoxide dismutase mimic.

Chaturvedi KS, Hung CS, Giblin DE, Urushidani S, Austin AM, Dinauer MC, Henderson JP - ACS Chem. Biol. (2013)

Cu(II)-Ybtis a superoxide dismutase mimic. Superoxide’sinteraction with Cu(II)-Ybt was probed in vitro withthe superoxide-generating xanthine/xanthine oxidase (XO) reactionsystem. (a) A dose–response relationship is observed betweenCu(II)-Ybt and SOD activity. (b) Cu(II)-Ybt concentrations remainunchanged following exposure to the intact xanthine/xanthine oxidasesystem. (c) In a complete reaction system, 10 μM Cu(II)-Ybtgenerates 0.04 μM hydrogen peroxide (H2O2) in the presence of superoxide anion, which is significantly (p = 0.0067, Mest) higher than the H2O2 generated in the presence of apo-Ybt alone or the negative control.(d) SOD ctivify is negligible for apo-Ybt alone but 63.12% and 41.4%for its Cu(II) andFe(III) complexes, respectively. This activity isabsent in complexes with the redox-inactive metal Ga(III). Resultsare reported as a normalized percentage compared to positive controlstreated with bovine superoxide dismutase. The data are presented asmeans ± SD of five independent experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3934373&req=5

fig4: Cu(II)-Ybtis a superoxide dismutase mimic. Superoxide’sinteraction with Cu(II)-Ybt was probed in vitro withthe superoxide-generating xanthine/xanthine oxidase (XO) reactionsystem. (a) A dose–response relationship is observed betweenCu(II)-Ybt and SOD activity. (b) Cu(II)-Ybt concentrations remainunchanged following exposure to the intact xanthine/xanthine oxidasesystem. (c) In a complete reaction system, 10 μM Cu(II)-Ybtgenerates 0.04 μM hydrogen peroxide (H2O2) in the presence of superoxide anion, which is significantly (p = 0.0067, Mest) higher than the H2O2 generated in the presence of apo-Ybt alone or the negative control.(d) SOD ctivify is negligible for apo-Ybt alone but 63.12% and 41.4%for its Cu(II) andFe(III) complexes, respectively. This activity isabsent in complexes with the redox-inactive metal Ga(III). Resultsare reported as a normalized percentage compared to positive controlstreated with bovine superoxide dismutase. The data are presented asmeans ± SD of five independent experiments.
Mentions: To determine the origin of SOD-likeactivity in copper-repletewild-type supernatants, we analyzed fractions by liquid chromatography–massspectrometry (LC–MS). The LC–MS chromatogram from the80% fraction was dominated by a single peak corresponding to Cu(II)-Ybt(Figure 3c). A preparation of purified Cu(II)-Ybtsimilarly exhibited SOD-like activity with a dose–responserelationship (Figure.4a). For 0.12, 0.6, 3.0,and 15.0 mM solutions of Cu(II)-Ybt, the percentage inhibition rateswere determined to be 4.6%, 19.8%, 24.3%, and 55.7%, respectively.

Bottom Line: Among these, the virulence-associated siderophore yersiniabactin (Ybt) is an avid copper chelator, forming stable cupric (Cu(II)-Ybt) complexes that are detectable in infected patients.Unlike previously described synthetic copper-salicylate (Cu(II)-SA) SOD mimics, the salicylate-based natural product Cu(II)-Ybt retains catalytic activity at physiologically plausible protein concentrations.These results reveal a new virulence-associated adaptation based upon spontaneous assembly of a non-protein catalyst.

View Article: PubMed Central - PubMed

Affiliation: Center for Women's Infectious Diseases Research, ‡Division of Infectious Diseases, §Department of Internal Medicine, ∥Department of Chemistry, ⊥Department of Pediatrics, and #Department of Pathology and Immunology, Washington University School of Medicine , St. Louis, Missouri 63110, United States.

ABSTRACT
Many Gram-negative bacteria interact with extracellular metal ions by expressing one or more siderophore types. Among these, the virulence-associated siderophore yersiniabactin (Ybt) is an avid copper chelator, forming stable cupric (Cu(II)-Ybt) complexes that are detectable in infected patients. Here we show that Ybt-expressing E. coli are protected from intracellular killing within copper-replete phagocytic cells. This survival advantage is highly dependent upon the phagocyte respiratory burst, during which superoxide is generated by the NADPH oxidase complex. Chemical fractionation links this phenotype to a previously unappreciated superoxide dismutase (SOD)-like activity of Cu(II)-Ybt. Unlike previously described synthetic copper-salicylate (Cu(II)-SA) SOD mimics, the salicylate-based natural product Cu(II)-Ybt retains catalytic activity at physiologically plausible protein concentrations. These results reveal a new virulence-associated adaptation based upon spontaneous assembly of a non-protein catalyst.

Show MeSH
Related in: MedlinePlus