The second cupredoxin domain of fungal laccase, diphenol oxidase
Diphenol oxidase belongs to the laccase family. It catalyzes the initial steps in melanin biosynthesis from diphenols. Melanin is one of the virulence factors of infectious fungi. In the pathogenesis of C. neoformans, melanin pigments have been shown to protect the fungal cells from oxidative and microbicidal activities of host defense systems. Laccase is a blue multi-copper enzyme that catalyzes the oxidation of a variety aromatic - notably phenolic and inorganic substances coupled to the reduction of molecular oxygen to water. It has been implicated in a wide spectrum of biological activities and, in particular, plays a key role in morphogenesis, development and lignin metabolism. Laccase is a multicopper oxidase (MCO) composed of three cupredoxin domains that include one mononuclear and one trinuclear copper center. 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 2 of 3-domain MCOs has lost the ability to bind copper.
Jiyao W et al.(2023). "The conserved domain database in 2023.",