soluble periplasm cuproprotein CucA and related proteins, cupin domain
This family includes bacterial proteins homologous to a soluble periplasm protein, CucA, found in the periplasm of the cyanobacterium Synechocystis where it shows some Cu2+-dependent quercetin dioxygenase activity. Studies show that a copper-trafficking pathway enables Cu2+ occupancy of CucA to accumulate in the periplasm, and this involves two copper transporters (CtaA and PacS) and a metallochaperone (Atx1). CucA belongs to the cupin superfamily with a conserved "jelly roll-like" beta-barrel fold capable of homodimerization.
Jiyao W et al.(2023). "The conserved domain database in 2023.",