Sphingobium sp. SYK-6 LigG involved in lignin degradation is structurally and biochemically related to the glutathione transferase omega class

SpLigG is one of the three glutathione transferases (GSTs) involved in the process of lignin breakdown in the soil bacterium Sphingobium sp. SYK-6. Sequence comparisons showed that SpLigG and several proteobacteria homologues form an independent cluster within cysteine-containing GSTs. The relationship between SpLigG and other GSTs was investigated. The X-ray structure and biochemical properties of SpLigG indicate that this enzyme belongs to the omega class of glutathione transferases. However, the hydrophilic substrate binding site of SpLigG, together with its known ability to stereoselectively deglutathionylate the physiological substrate α-glutathionyl-β-hydroxypropiovanillone, argues for broadening the definition of the omega class.Structured summary of protein interactionsSpLigG and SpLigGbind by X-ray crystallography (View interaction).

► Sphingobium sp. SYK-6 LigG is a glutathione transferase with a catalytic cysteine. ► SpLigG shows activity towards HED, DHA, and α-glutathionyl-β-hydroxypropiovanillone. ► The SpLigG crystal structure at 1.2 Å resolution was compared to other known GST structures. ► SpLigG belongs to the omega class of GSTs, but shows structural and substrate specificities.