Thioredoxin reductase (Giardia lamblia) (TrxR)

Thioredoxin reductase (TrxR) from Giardia lamblia is a critical homodimeric flavoenzyme responsible for maintaining the parasite's intracellular redox environment (Müller et al., 2007, PubMed: 17606115). Unlike many eukaryotes, Giardia lacks the glutathione-glutathione reductase system, making it uniquely dependent on the thioredoxin system to combat oxidative stress and provide reducing equivalents for DNA synthesis (UniProt P90551). The enzyme catalyzes the NADPH-dependent reduction of thioredoxin, which in turn reduces various downstream targets. Because of its essential role and structural differences from the human counterpart—specifically the absence of a selenocysteine residue in the parasite's low-molecular-weight TrxR—it is a high-priority target for anti-parasitic drug development (Tejman-Yarden et al., 2013, PubMed: 23504152). Drugs like auranofin have demonstrated potent inhibitory activity against Giardia TrxR, offering a potential alternative for treating metronidazole-resistant infections.

Other names

NADPH-dependent thioredoxin reductaseGlTrxRThioredoxin-disulfide reductase

Inhibition of thioredoxin reductase prevents the reduction of thioredoxin, leading to an accumulation of reactive oxygen species, oxidative damage, and impaired DNA synthesis, ultimately resulting in parasite death (Tejman-Yarden et al., 2013, PubMed: 23504152).