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Thioredoxin reductase from Toxoplasma gondii : an essential virulence effector with antioxidant function
Author(s) -
Xue Junxin,
Jiang Wei,
Chen Yongjun,
Gong Fengju,
Wang Minyan,
Zeng Peng,
Xia Can,
Wang Quan,
Huang Kehe
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.201700008r
Subject(s) - toxoplasma gondii , virulence , effector , thioredoxin , thioredoxin reductase , function (biology) , biology , antioxidant , apicoplast , microbiology and biotechnology , oxidative stress , biochemistry , genetics , immunology , apicomplexa , gene , antibody , malaria , plasmodium falciparum
Thioredoxin reductase (TR) can help pathogens resist oxidative‐burst injury from host immune cells by maintaining a thioredoxin‐reduction state during NADPH consumption. TR is a necessary virulence factor that enables the persistent infection of some parasites. We performed bioinformatics analyses and biochemical assays to characterize the activity, subcellular localization, and genetic ablation of Toxoplasma gondii TR (TgTR), to shed light on its biologic function. We expressed the TgTR protein with an Escherichia coli expression system and analyzed its enzyme activity, reporting a K m for the recombinant TgTR of 11.47–15.57 μM, using NADPH as a substrate, and 130.48–151.09 μM with dithio‐bis‐nitrobenzoic acid as a substrate. The TgTR sequence shared homology with that of TR, but lacked a selenocysteine residue in the C‐terminal region and was thought to contain 2 flavin adenine dinucleotide (FAD) domains and 1 NADPH domain. In addition, immunoelectron microscopy results showed that TgTR was widely dispersed in the cytoplasm, and we observed that parasite antioxidant capacity, invasion efficiency, and proliferation were decreased in TR‐knockout (TR‐KO) strains in vitro, although this strain still stimulated the release of reactive oxygen species release in mouse macrophages while being more sensitive to H 2 O 2 toxicity in vitro . Furthermore, our in vivo results revealed that the survival time of mice infected with the TR‐KO strain was significantly prolonged relative to that of mice infected with the wild‐type strain. These results suggest that TgTR plays an important role in resistance to oxidative damage and can be considered a virulence factor associated with T. gondii infection.—Xue, J., Jiang, W., Chen, Y., Gong, F., Wang, M., Zeng, P., Xia, C., Wang, Q., Huang, K. Thioredoxin reductase from Toxoplasma gondii : an essential virulence effector with antioxidant function. FASEB J. 31, 4447–4457 (2017). www.fasebj.org