Inactivation, complementation, and heterologous expression of encP, a novel bacterial phenylalanine ammonia-lyase...

The enzyme phenylalanine ammonia-lyase, which catalyzes the nonoxidative deamination of l-phenylalanine to trans-cinnamic acid, is ubiquitously distributed in plants. We now report its characterization for the first time in a bacterium. The phenylalanine ammonia-lyase homologous gene encP from the "Streptomyces maritimus" enterocin biosynthetic gene cluster was functionally characterized and shown to encode the first enzyme in the pathway to the enterocin polyketide synthase starter unit benzoyl-coenzyme A. The disruption of the encP gene completely inhibited the production of cinnamate and enterocin, whereas complementation of the mutant with benzoyl-coenzyme A pathway intermediates or with the wild-type gene encP restored the formation of the benzoate-primed polyketide antibiotic enterocin. Heterologous expression of the encP gene under the control of the ermE* promoter in Streptomyces coelicolor furthermore led to the production of cinnamic acid in the fermented cultures, confirming that the encP gene indeed encodes a novel bacterial phenylalanine ammonia-lyase.