Thioredoxin 1 regulation of protein S-desulfhydration

Abstract The importance of H 2 S in biology and medicine has been widely recognized in recent years, and protein S- sulfhydration is proposed to mediate the direct actions of H 2 S bioactivity in the body. Thioredoxin 1 (Trx1) is an important reducing enzyme that cleaves disulfides in proteins and acts as an S -denitrosylase. The regulation of Trx1 on protein S -sulfhydration is unclear. Here we showed that Trx1 facilitates protein S -desulfhydration. Overexpression of Trx1 attenuated the basal level and H 2 S-induced protein S -sulfhydration by direct interaction with S -sulfhydrated proteins, i.e., glyceraldehyde 3-phosphate dehydrogenase and pyruvate carboxylase. In contrast, knockdown of Trx1 mRNA expression by short interfering RNA or blockage of Trx1 redox activity with PX12 or 2,4-dinitrochlorobenzene enhanced protein S -sulfhydration. Mutation of cysteine-32 but not cysteine-35 in the Trp–Cys 32 –Gly–Pro–Cys 35 motif eliminated the binding of Trx1 with S -sulfhydrated proteins and abolished the S -desulfhydrating effect of Trx1. All these data suggest that Trx1 acts as an S -desulfhydrase.