HighlightsThe first PPO gene (cgAUS1) involved in 4-deoxyaurone formation is identified.AUS1 is expressed as latent pro-enzyme in E. coli and purified to homogeneity.Diphenolase activity of AUS1 pro-enzyme is proven using SDS as an activation agent.Gene expression studies suggest a physiological role for AUS1 in aurone formation.

No abstract

HighlightsSite-directed mutations of AUS1 around the CuA site were generated and verified.All mutations led to loss of diphenolase activity with butein as substrate.Exchange of histidines in the CuA resulted in enzymes containing only one Cu.F273 mutation to alanine did not increase the monophenolase activity.C97 mutation eliminated the diphenolase activity, but 2 Cu atoms were incorporated.