Glutathione- and glutaredoxin-dependent reduction of methionine sulfoxide reductase A

► A Grx-Grx-MsrA fusion catalyzes the glutathione-dependent reduction of MetO. ► Plant-type MsrAs are recycled both by thioredoxins and glutaredoxins. ► A catalytic mechanism for the Grx-dependent regeneration of 3-Cys MsrA is proposed. ► Natural hybrid proteins help identifying protein interactions in other organisms.