This is the N-terminal domain found in Diiron non-heme beta-hydroxylase (CmlA). CmlA catalyzes beta-hydroxylation of the precursor molecule l-p-aminophenylalanine (l-PAPA) to form l-p-aminophenylserine. Structural analysis indicate that the N-terminal domain facilitates dimerization and has a mixed alpha-beta topology. Furthermore, a projecting 'dimerization arm' (residues 108-146) from the N-terminal domain of CmlA mediates the interaction between the monomers [1].

1: Structure of a dinuclear iron cluster-containing beta-hydroxylase active in antibiotic biosynthesis. Makris TM, Knoot CJ, Wilmot CM, Lipscomb JD; Biochemistry. 2013;52:6662-6671. PMID:23980641