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  -