Oxidizing substrate specificity of Mycobacterium tuberculosis alkyl hydroperoxide reductase E: kinetics and mechanisms of oxidation and overoxidation

Reyes, Aníbal M.; Hugo, Martín; Trostchansky, Andrés; Capece, Luciana; Radí, Rafael; Trujillo, Madia

doi:10.1016/j.freeradbiomed.2011.04.023

Cited by 43 publications

(69 citation statements)

References 52 publications

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“…Peroxynitrite (0.5 μM) caused a rapid decrease in total fluorescence intensity (λ ex = 295 nm) of reduced MtAhpE (2.5 μM). The exponential fitting of the experimental curve was consistent with a rate constant of peroxynitritemediated MtAhpE oxidation of 1.1 × 10 7 M −1 ·s −1 at pH 7.4 and 25°C, in close agreement to the previously reported value (8). Reduced XfOhr dose-dependently inhibited the decrease in fluorescence of MtAhpE caused by peroxynitrite, consistent with a rate constant between peroxynitrite and XfOhr of (2.0 ± 0.3) ≥ 10 7 M −1 ·s −1 at pH 7.4 and 25°C (Fig.…”

Section: Resultssupporting

confidence: 91%

“…For other Cys-based peroxidases, substrate specificity correlates well with hyperoxidation rates (8,(37)(38)(39), which is consistent with the fact that oxidation to Cys-SOH and hyperoxidation are both reactions dependent on hydroperoxide concentration (Fig. 3A).…”

Section: Resultssupporting

confidence: 81%

“…A competition method was developed here, taking advantage of the fact that Ohr from X. fastidiosa and P. aeruginosa does not possess Trp residues, and consequently displays low intrinsic fluorescence. In contrast, MtAhpE has intrinsic fluorescence that decreases upon oxidation (8,55). As expected, XfOhr practically lacks intrinsic fluorescence when excited at 295 nm, in contrast to MtAhpE (Fig.…”

Section: Methodssupporting

confidence: 64%

“…A second example is the competition between the two peroxidases for H 2 O 2 , considering that the rate constant of MtAhpE for H 2 O 2 is 8.1 × 10 4 M −1 ·s −1 (8). We observed that only at very high concentrations (10-30 μM) was XfOhr able to inhibit MtAhpE (2 μM) oxidation (Fig.…”

Section: Resultsmentioning

confidence: 73%

“…The t-BHP was obtained from Sigma-Aldrich Co. CHP and H 2 O 2 were obtained Merck KGaA. XfOhr and PaOhr, as well as MtAhpE, were obtained and, in some experiments, reduced as previously described (8,55). The 15(S)-HpETE and 5(S)-HpETE were purchased from Cayman Chemical.…”

Section: Methodsmentioning

confidence: 99%

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Ohr plays a central role in bacterial responses against fatty acid hydroperoxides and peroxynitrite

Alegria

Meireles

Cussiol

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Organic hydroperoxide resistance (Ohr) enzymes are unique Cysbased, lipoyl-dependent peroxidases. Here, we investigated the involvement of Ohr in bacterial responses toward distinct hydroperoxides. In silico results indicated that fatty acid (but not cholesterol) hydroperoxides docked well into the active site of Ohr from Xylella fastidiosa and were efficiently reduced by the recombinant enzyme as assessed by a lipoamide-lipoamide dehydrogenase-coupled assay. Indeed, the rate constants between Ohr and several fatty acid hydroperoxides were in the 10 7 -10 8 M −1 ·s −1 range as determined by a competition assay developed here. Reduction of peroxynitrite by Ohr was also determined to be in the order of 10 7 M −1 ·s −1 at pH 7.4 through two independent competition assays. A similar trend was observed when studying the sensitivities of a Δohr mutant of Pseudomonas aeruginosa toward different hydroperoxides. Fatty acid hydroperoxides, which are readily solubilized by bacterial surfactants, killed the Δohr strain most efficiently. In contrast, both wild-type and mutant strains deficient for peroxiredoxins and glutathione peroxidases were equally sensitive to fatty acid hydroperoxides. Ohr also appeared to play a central role in the peroxynitrite response, because the Δohr mutant was more sensitive than wild type to 3-morpholinosydnonimine hydrochloride (SIN-1 , a peroxynitrite generator). In the case of H 2 O 2 insult, cells treated with 3-amino-1,2,4-triazole (a catalase inhibitor) were the most sensitive. Furthermore, fatty acid hydroperoxide and SIN-1 both induced Ohr expression in the wildtype strain. In conclusion, Ohr plays a central role in modulating the levels of fatty acid hydroperoxides and peroxynitrite, both of which are involved in host-pathogen interactions.hydroperoxides | thiols | Cys-based peroxidase | pathogenic bacteria | Pseudomonas aeruginosa

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 81%

Section: Methodssupporting

confidence: 64%

Section: Resultsmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Ohr plays a central role in bacterial responses against fatty acid hydroperoxides and peroxynitrite

Alegria

Meireles

Cussiol

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Relevance of peroxiredoxins in pathogenic microorganisms

Oliveira

Tairum

Netto

et al. 2021

Appl Microbiol Biotechnol

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Thiol redox biochemistry: insights from computer simulations

et al. 2014

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Thiol redox chemical reactions play a key role in a variety of physiological processes, mainly due to the presence of low-molecular-weight thiols and cysteine residues in proteins involved in catalysis and regulation. Specifically, the subtle sensitivity of thiol reactivity to the environment makes the use of simulation techniques extremely valuable for obtaining microscopic insights. In this work we review the application of classical and quantum-mechanical atomistic simulation tools to the investigation of selected relevant issues in thiol redox biochemistry, such as investigations on (1) the protonation state of cysteine in protein, (2) two-electron oxidation of thiols by hydroperoxides, chloramines, and hypochlorous acid, (3) mechanistic and kinetics aspects of the de novo formation of disulfide bonds and thiol−disulfide exchange, (4) formation of sulfenamides, (5) formation of nitrosothiols and transnitrosation reactions, and (6) oneelectron oxidation pathways.

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Oxidizing substrate specificity of Mycobacterium tuberculosis alkyl hydroperoxide reductase E: kinetics and mechanisms of oxidation and overoxidation

Cited by 43 publications

References 52 publications

Ohr plays a central role in bacterial responses against fatty acid hydroperoxides and peroxynitrite

Ohr plays a central role in bacterial responses against fatty acid hydroperoxides and peroxynitrite

Relevance of peroxiredoxins in pathogenic microorganisms

Thiol redox biochemistry: insights from computer simulations

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