Catalyzes the formation of an amide bond between 3-dimethylallyl-4-hydroxybenzoate (ring A of novobiocin) and 3-amino-4,7-dihydroxycoumarin (ring B of novobiocin) in an ATP-dependent reaction in the novobiocin biosynthesis pathway. Novobiocin is an aminocoumarin family antibiotic that targets bacterial DNA gyrases. 3-amino-4,7-dihydroxycoumarin + 3-dimethylallyl-4-hydroxybenzoate + ATP = 8-desmethylnovobiocic acid + AMP + diphosphate Optimum pH is 8.0. Antibiotic biosynthesis; novobiocin biosynthesis. Monomer. Belongs to the ATP-dependent AMP-binding enzyme family.