Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase

Tijana Jovanović, Carla Ascenso, Karsten R.O. Hazlett, Robert Sikkink, Carsten Krebs, Robert Litwiller, Linda M. Benson, Isabel Moura, Jose J.G. Moura, Justin D. Radolf, Boi Hanh Huynh, Stephen Naylor, Frank Rusnak

Research output: Contribution to journalArticle

89 Citations (Scopus)

Abstract

Treponema pallidum, the causative agent of venereal syphilis, is a microaerophilic obligate pathogen of humans. As it disseminates hematogenously and invades a wide range of tissues, T. pallidum presumably must tolerate substantial oxidative stress. Analysis of the T. pallidum genome indicates that the syphilis spirochete lacks most of the iron-binding proteins present in many other bacterial pathogens, including the oxidative defense enzymes superoxide dismutase, catalase, and peroxidase, but does possess an orthologue (TP0823) for neelaredoxin, an enzyme of hyperthermophilic and sulfate-reducing anaerobes shown to possess superoxide reductase activity. To analyze the potential role of neelaredoxin in treponemal oxidative defense, we examined the biochemical, spectroscopic, and antioxidant properties of recombinant T. pallidum neelaredoxin. Neelaredoxin was shown to be expressed in T. pallidum by reverse transcriptase-polymerase chain reaction and Western blot analysis. Recombinant neelaredoxin is a 26-kDa α2 homodimer containing, on average, 0.7 iron atoms/subunit. Mossbauer and EPR analysis of the purified protein indicates that the iron atom exists as a mononuclear center in a mixture of high spin ferrous and ferric oxidation states. The fully oxidized form, obtained by the addition of K3(Fe (CN)6), exhibits an optical spectrum with absorbances at 280, 320, and 656 nm; the last feature is responsible for the protein's blue color, which disappears upon ascorbate reduction. The fully oxidized protein has a A280/A656 ratio of 10.3. Enzymatic studies revealed that T. pallidum neelaredoxin is able to catalyze a redox equilibrium between superoxide and hydrogen peroxide, a result consistent with it being a superoxide reductase. This finding, the first description of a T. pallidum iron-binding protein, indicates that the syphilis spirochete copes with oxidative stress via a primitive mechanism, which, thus far, has not been described in pathogenic bacteria.

Original languageEnglish (US)
Pages (from-to)28439-28448
Number of pages10
JournalJournal of Biological Chemistry
Volume275
Issue number37
DOIs
StatePublished - Sep 15 2000

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Iron-Binding Proteins
Treponema pallidum
Spirochaetales
Syphilis
Oxidative stress
Pathogens
Iron
Oxidative Stress
Atoms
Proteins
Polymerase chain reaction
RNA-Directed DNA Polymerase
Enzymes
Superoxides
Catalase
Hydrogen Peroxide
Peroxidase
Sulfates
Superoxide Dismutase
Paramagnetic resonance

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Jovanović, Tijana ; Ascenso, Carla ; Hazlett, Karsten R.O. ; Sikkink, Robert ; Krebs, Carsten ; Litwiller, Robert ; Benson, Linda M. ; Moura, Isabel ; Moura, Jose J.G. ; Radolf, Justin D. ; Huynh, Boi Hanh ; Naylor, Stephen ; Rusnak, Frank. / Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 37. pp. 28439-28448.
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abstract = "Treponema pallidum, the causative agent of venereal syphilis, is a microaerophilic obligate pathogen of humans. As it disseminates hematogenously and invades a wide range of tissues, T. pallidum presumably must tolerate substantial oxidative stress. Analysis of the T. pallidum genome indicates that the syphilis spirochete lacks most of the iron-binding proteins present in many other bacterial pathogens, including the oxidative defense enzymes superoxide dismutase, catalase, and peroxidase, but does possess an orthologue (TP0823) for neelaredoxin, an enzyme of hyperthermophilic and sulfate-reducing anaerobes shown to possess superoxide reductase activity. To analyze the potential role of neelaredoxin in treponemal oxidative defense, we examined the biochemical, spectroscopic, and antioxidant properties of recombinant T. pallidum neelaredoxin. Neelaredoxin was shown to be expressed in T. pallidum by reverse transcriptase-polymerase chain reaction and Western blot analysis. Recombinant neelaredoxin is a 26-kDa α2 homodimer containing, on average, 0.7 iron atoms/subunit. Mossbauer and EPR analysis of the purified protein indicates that the iron atom exists as a mononuclear center in a mixture of high spin ferrous and ferric oxidation states. The fully oxidized form, obtained by the addition of K3(Fe (CN)6), exhibits an optical spectrum with absorbances at 280, 320, and 656 nm; the last feature is responsible for the protein's blue color, which disappears upon ascorbate reduction. The fully oxidized protein has a A280/A656 ratio of 10.3. Enzymatic studies revealed that T. pallidum neelaredoxin is able to catalyze a redox equilibrium between superoxide and hydrogen peroxide, a result consistent with it being a superoxide reductase. This finding, the first description of a T. pallidum iron-binding protein, indicates that the syphilis spirochete copes with oxidative stress via a primitive mechanism, which, thus far, has not been described in pathogenic bacteria.",
author = "Tijana Jovanović and Carla Ascenso and Hazlett, {Karsten R.O.} and Robert Sikkink and Carsten Krebs and Robert Litwiller and Benson, {Linda M.} and Isabel Moura and Moura, {Jose J.G.} and Radolf, {Justin D.} and Huynh, {Boi Hanh} and Stephen Naylor and Frank Rusnak",
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Jovanović, T, Ascenso, C, Hazlett, KRO, Sikkink, R, Krebs, C, Litwiller, R, Benson, LM, Moura, I, Moura, JJG, Radolf, JD, Huynh, BH, Naylor, S & Rusnak, F 2000, 'Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase', Journal of Biological Chemistry, vol. 275, no. 37, pp. 28439-28448. https://doi.org/10.1074/jbc.M003314200

Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase. / Jovanović, Tijana; Ascenso, Carla; Hazlett, Karsten R.O.; Sikkink, Robert; Krebs, Carsten; Litwiller, Robert; Benson, Linda M.; Moura, Isabel; Moura, Jose J.G.; Radolf, Justin D.; Huynh, Boi Hanh; Naylor, Stephen; Rusnak, Frank.

In: Journal of Biological Chemistry, Vol. 275, No. 37, 15.09.2000, p. 28439-28448.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Neelaredoxin, an iron-binding protein from the syphilis spirochete, Treponema pallidum, is a superoxide reductase

AU - Jovanović, Tijana

AU - Ascenso, Carla

AU - Hazlett, Karsten R.O.

AU - Sikkink, Robert

AU - Krebs, Carsten

AU - Litwiller, Robert

AU - Benson, Linda M.

AU - Moura, Isabel

AU - Moura, Jose J.G.

AU - Radolf, Justin D.

AU - Huynh, Boi Hanh

AU - Naylor, Stephen

AU - Rusnak, Frank

PY - 2000/9/15

Y1 - 2000/9/15

N2 - Treponema pallidum, the causative agent of venereal syphilis, is a microaerophilic obligate pathogen of humans. As it disseminates hematogenously and invades a wide range of tissues, T. pallidum presumably must tolerate substantial oxidative stress. Analysis of the T. pallidum genome indicates that the syphilis spirochete lacks most of the iron-binding proteins present in many other bacterial pathogens, including the oxidative defense enzymes superoxide dismutase, catalase, and peroxidase, but does possess an orthologue (TP0823) for neelaredoxin, an enzyme of hyperthermophilic and sulfate-reducing anaerobes shown to possess superoxide reductase activity. To analyze the potential role of neelaredoxin in treponemal oxidative defense, we examined the biochemical, spectroscopic, and antioxidant properties of recombinant T. pallidum neelaredoxin. Neelaredoxin was shown to be expressed in T. pallidum by reverse transcriptase-polymerase chain reaction and Western blot analysis. Recombinant neelaredoxin is a 26-kDa α2 homodimer containing, on average, 0.7 iron atoms/subunit. Mossbauer and EPR analysis of the purified protein indicates that the iron atom exists as a mononuclear center in a mixture of high spin ferrous and ferric oxidation states. The fully oxidized form, obtained by the addition of K3(Fe (CN)6), exhibits an optical spectrum with absorbances at 280, 320, and 656 nm; the last feature is responsible for the protein's blue color, which disappears upon ascorbate reduction. The fully oxidized protein has a A280/A656 ratio of 10.3. Enzymatic studies revealed that T. pallidum neelaredoxin is able to catalyze a redox equilibrium between superoxide and hydrogen peroxide, a result consistent with it being a superoxide reductase. This finding, the first description of a T. pallidum iron-binding protein, indicates that the syphilis spirochete copes with oxidative stress via a primitive mechanism, which, thus far, has not been described in pathogenic bacteria.

AB - Treponema pallidum, the causative agent of venereal syphilis, is a microaerophilic obligate pathogen of humans. As it disseminates hematogenously and invades a wide range of tissues, T. pallidum presumably must tolerate substantial oxidative stress. Analysis of the T. pallidum genome indicates that the syphilis spirochete lacks most of the iron-binding proteins present in many other bacterial pathogens, including the oxidative defense enzymes superoxide dismutase, catalase, and peroxidase, but does possess an orthologue (TP0823) for neelaredoxin, an enzyme of hyperthermophilic and sulfate-reducing anaerobes shown to possess superoxide reductase activity. To analyze the potential role of neelaredoxin in treponemal oxidative defense, we examined the biochemical, spectroscopic, and antioxidant properties of recombinant T. pallidum neelaredoxin. Neelaredoxin was shown to be expressed in T. pallidum by reverse transcriptase-polymerase chain reaction and Western blot analysis. Recombinant neelaredoxin is a 26-kDa α2 homodimer containing, on average, 0.7 iron atoms/subunit. Mossbauer and EPR analysis of the purified protein indicates that the iron atom exists as a mononuclear center in a mixture of high spin ferrous and ferric oxidation states. The fully oxidized form, obtained by the addition of K3(Fe (CN)6), exhibits an optical spectrum with absorbances at 280, 320, and 656 nm; the last feature is responsible for the protein's blue color, which disappears upon ascorbate reduction. The fully oxidized protein has a A280/A656 ratio of 10.3. Enzymatic studies revealed that T. pallidum neelaredoxin is able to catalyze a redox equilibrium between superoxide and hydrogen peroxide, a result consistent with it being a superoxide reductase. This finding, the first description of a T. pallidum iron-binding protein, indicates that the syphilis spirochete copes with oxidative stress via a primitive mechanism, which, thus far, has not been described in pathogenic bacteria.

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