Involved in chloramphenicol biosynthesis (PubMed:20713732). Catalyzes the beta-hydroxylation of 4-amino-L-phenylalanine (L-PAPA) covalently bound to CmlP to form L-p-aminophenylserine (PubMed:20713732). 4-amino-L-phenylalanyl-[peptidyl-carrier protein] + AH2 + O2 = (2R)-2-(4-aminophenyl)-L-seryl-[peptidyl-carrier protein] + A + H2O Contains a dinuclear iron cluster that becomes oxo-bridged (Fe-O-Fe) during O(2) activation. Antibiotic biosynthesis. Homodimer. Belongs to the metallo-beta-lactamase superfamily.