Pseudomonas aeruginosa possesses homologues of mammalian phenylalanine hydroxylase and 4 alpha-carbinolamine dehydratase/DCoH as part of a three-component gene cluster.

Pseudomonas aeruginosa possesses a multigeneoperon that includes phenylalanine hydroxylase (PhhA; phenylalanine4-monooxygenase, EC 1.14.16.1). phhA encodes PhhA (M(r) = 30,288), phhB (M(r) =13,333) encodes a homologue of mammalian 4 alpha-carbinolaminedehydratase/homeodomain protein transregulator, and phhC encodes an aromaticaminotransferase (M(r) = 43,237). The reading frames specifying phhB and phhCoverlap by 2 bases. The P. aeruginosa PhhA appears to contain iron and is pterindependent. Unlike the multimeric mammalian hydroxylase, the native P. aeruginosaenzyme is a monomer. The P. aeruginosa PhhA is homologous with mammalian PhhA,tryptophan hydroxylase, and tyrosine hydroxylase. Expression of PhhA from itsnative promoter required phhB. This may suggest a positive regulatory role forphhB, consistent with the dual catalytic and regulatory roles of thecorresponding mammalian homologue.