Glutathionyl-hydroquinone reductases from poplar are plastidial proteins that deglutathionylate both reduced and oxidized glutathionylated quinones

• Poplar GHRs are found exclusively in plastids, particularly in reproductive organs.
• Poplar GHR1 catalyzes the deglutathionylation of oxidized and reduced quinones.
• The residues forming the dimeric interface of poplar GHR1 are conserved.

Glutathionyl-hydroquinone reductases (GHRs) catalyze the deglutathionylation of quinones via a catalytic cysteine. The two GHR genes in the Populus trichocarpa genome, Pt-GHR1 and Pt-GHR2, are primarily expressed in reproductive organs. Both proteins are localized in plastids. More specifically, Pt-GHR2 localizes in nucleoids. At the structural level, Pt-GHR1 adopts a typical GHR fold, with a dimerization interface comparable to that of the bacterial and fungal GHR counterparts. Pt-GHR1 catalyzes the deglutathionylation of both reduced and oxidized glutathionylated quinones, but the enzyme is more catalytically efficient with the reduced forms.