The third Cupredoxin domain of phenoxazinone synthase (PHS)
Phenoxazinone synthase (PHS, 2-aminophenol:oxygen oxidoreductase) catalyzes the oxidative coupling of substituted o-aminophenols to produce phenoxazinones. PHS has been shown to participate in diverse biological functions such as spore pigmentation and biosynthesis of the antibiotic grixazone. PHS is a member of the laccase-like multicopper oxidase (MCO) family, which are able to couple oxidation of substrates with reduction of dioxygen to water. MCOs are capable of oxidizing a vast range of substrates, varying from aromatic compounds to inorganic compounds such as metals. Although the members of this family have diverse functions, majority of them have three cupredoxin domain repeats. The copper ions are bound in several sites: Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster. MCOs oxidize their substrate by accepting electrons at a mononuclear copper center and transferring them to the active site trinuclear copper center. The cupredoxin domain 3 of 3-domain MCOs contains the Type 1 (T1) copper binding site and part the trinuclear copper binding site, which is located at the interface of domains 1 and 3.
Jiyao W et al.(2023). "The conserved domain database in 2023.",