TY  - JOUR
A1  - Reyes, Anibal M.
A1  - Vazquez, Diego S.
A1  - Zeida, Ari
A1  - Hugo, Martin
A1  - Dolores Pineyro, M.
A1  - Ines De Armas, Maria
A1  - Estrin, Dario
A1  - Radi, Rafael
A1  - Santos, Javier
A1  - Trujillo, Madia
T1  - PrxQ B from Mycobacterium tuberculosis is a monomeric, thioredoxin-dependent and highly efficient fatty acid hydroperoxide reductase
JF  - Free radical biology and medicine : the official journal of the Oxygen Society, a constituent member of the International Society for Free Radical Research
N2  - Mycobacterium tuberculosis (M. tuberculosis) is the intracellular bacterium responsible for tuberculosis disease (TD). Inside the phagosomes of activated macrophages, M. tuberculosis is exposed to cytotoxic hydroperoxides such as hydrogen peroxide, fatty acid hydroperoxides and peroxynitrite. Thus, the characterization of the bacterial antioxidant systems could facilitate novel drug developments. In this work, we characterized the product of the gene Rv1608c from M. tuberculosis, which according to sequence homology had been annotated as a putative peroxiredoxin of the peroxiredoxin Q subfamily (PrxQ B from M. tuberculosis or MtPrxQ B). The protein has been reported to be essential for M. tuberculosis growth in cholesterol-rich medium. We demonstrated the M. tuberculosis thioredoxin B/C-dependent peroxidase activity of MtPrxQ B, which acted as a two-cysteine peroxiredoxin that could function, although less efficiently, using a one-cysteine mechanism. Through steady-state and competition kinetic analysis, we proved that the net forward rate constant of MtPrxQ B reaction was 3 orders of magnitude faster for fatty acid hydroperoxides than for hydrogen peroxide (3x10(6) vs 6x10(3) M-1 s(-1), respectively), while the rate constant of peroxynitrite reduction was (0.6-1.4) x10(6) M-1 s(-1) at pH 7.4. The enzyme lacked activity towards cholesterol hydroperoxides solubilized in sodium deoxycholate. Both thioredoxin B and C rapidly reduced the oxidized form of MtPrxQ B, with rates constants of 0.5x10(6) and 1x10(6) M-1 s(-1), respectively. Our data indicated that MtPrxQ B is monomeric in solution both under reduced and oxidized states. In spite of the similar hydrodynamic behavior the reduced and oxidized forms of the protein showed important structural differences that were reflected in the protein circular dichroism spectra.
KW  - Mycobacterium tuberculosis
KW  - Peroxiredoxin
KW  - Thioredoxin
KW  - Peroxynitrite
KW  - Fatty acid hydroperoxides
KW  - Thiol-dependent peroxidase
KW  - Peroxidatic and resolving cysteine
Y1  - 2016
U6  - https://doi.org/10.1016/j.freeradbiomed.2016.10.005
SN  - 0891-5849
SN  - 1873-4596
VL  - 101
SP  - 249
EP  - 260
PB  - Elsevier
CY  - New York
ER  - 
TY  - JOUR
A1  - Ruszkiewicz, Joanna A.
A1  - de Macedo, Gabriel Teixeira
A1  - Miranda-Vizuete, Antonio
A1  - Teixeira da Rocha, Joao B.
A1  - Bowman, Aaron B.
A1  - Bornhorst, Julia
A1  - Schwerdtle, Tanja
A1  - Aschner, Michael
T1  - The cytoplasmic thioredoxin system in Caenorhabditis elegans affords protection from methylmercury in an age-specific manner
JF  - Neurotoxicology : the interdisciplinary journal of effects to toxic substances on the nervous system
N2  - Methylmercury (MeHg) is an environmental pollutant linked to many neurological defects, especially in developing individuals. The thioredoxin (TRX) system is a key redox regulator affected by MeHg toxicity, however the mechanisms and consequences of MeHg-induced dysfunction are not completely understood. This study evaluated the role of the TRX system in C. elegans susceptibility to MeHg during development. Worms lacking or overexpressing proteins from the TRX family were exposed to MeHg for 1 h at different developmental stage: L1, L4 and adult. Worms without cytoplasmic thioredoxin system exhibited age-specific susceptibility to MeHg when compared to wild-type (wt). This susceptibility corresponded partially to decreased total glutathione (GSH) levels and enhanced degeneration of dopaminergic neurons. In contrast, the overexpression of the cytoplasmic system TRX-1/TRXR-1 did not provide substantial protection against MeHg. Moreover, transgenic worms exhibited decreased protein expression for cytoplasmic thioredoxin reductase (TRXR-1). Both mitochondrial thioredoxin system TRX-2/TRXR-2, as well as other thioredoxin-like proteins: TRX-3, TRX-4, TRX-5 did not show significant role in C. elegans resistance to MeHg. Based on the current findings, the cytoplasmic thioredoxin system TRX-1/TRXR-1 emerges as an important age-sensitive protectant against MeHg toxicity in C. elegans.
KW  - Methylmercury
KW  - Age
KW  - Development
KW  - C. elegans
KW  - Thioredoxin
KW  - Thioredoxin reductase
Y1  - 2018
U6  - https://doi.org/10.1016/j.neuro.2018.08.007
SN  - 0161-813X
SN  - 1872-9711
VL  - 68
SP  - 189
EP  - 202
PB  - Elsevier
CY  - Amsterdam
ER  -