Involved in the transfer of copper ion to the apo form O-aminophenol oxidase GriF in the grixazone biosynthetic pathway. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. Cells lacking griE and griF show accumulation of the 3-amino-4-hydroxybenzaldehyde (3,4-AHBAL) intermediate. Belongs to the melC1 family.