A bacterial enzyme degrading the model lignin compound β‐etherase is a member of the glutathione‐S‐transferase superfamily

Cleavage of beta-aryl ether linkages is essential in lignin degradation. We identified another beta-etherase gene (ligF), which contains an open reading frame of 771 bp and lies between genes coding C alpha-dehydrogenase (ligD) and beta-etherase (ligE). The beta-etherase activity of LigF expressed in Escherichia coli was more than 80 times as high as that of LigE. ligF and ligE are homologous to glutathione-S-transferase, and upon addition of glutathione a remarkable acceleration of beta-etherase activity was found in E. coli carrying ligF. It is concluded that LigF plays a central role in beta-aryl ether cleavage and that glutathione is the hydrogen donor in this reaction.