L-3-(2,5-dihydrophenyl)alanine, an antimetabolite of L-phenylalanine produced by a streptomycete

The shikimate pathway: gateway to metabolic diversity

Covering: 1997 to 2023The shikimate pathway is the metabolic process responsible for the biosynthesis of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. Seven metabolic steps convert phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P) into shikimate and ultimately chorismate, which serves as the branch point for dedicated aromatic amino acid biosynthesis. Bacteria, fungi, algae, and plants (yet not animals) biosynthesize chorismate and exploit its intermediates in their specialized metabolism. This review highlights the metabolic diversity derived from intermediates of the shikimate pathway along the seven steps from PEP and E4P to chorismate, as well as additional sections on compounds derived from prephenate, anthranilate and the synonymous aminoshikimate pathway. We discuss the genomic basis and biochemical support leading to shikimate-derived antibiotics, lipids, pigments, cofactors, and other metabolites across the tree of life.

Dihydrophenylalanine: a prephenate-derived Photorhabdus luminescens antibiotic and intermediate in dihydrostilbene biosynthesis

2,5-Dihydrophenylalanine (H(2)Phe) is a multipotent nonproteinogenic amino acid produced by various Actinobacteria and Gammaproteobacteria. Although the metabolite was discovered over 40 years ago, details of its biosynthesis have remained largely unknown. We show here that L-H(2)Phe is a secreted metabolite in Photorhabdus luminescens cultures and a precursor of a recently described 2,5-dihydrostilbene. Bioinformatic analysis suggested a candidate gene cluster for the processing of prephenate to H(2)Phe, and gene knockouts validated that three adjacent genes plu3042-3044 were required for H(2)Phe production. Biochemical experiments validated Plu3043 as a nonaromatizing prephenate decarboxylase generating an endocyclic dihydro-hydroxyphenylpyruvate. Plu3042 acted next to transaminate the Plu3043 product, precluding spontaneous exocyclic double-bond isomerization and yielding 2,5-dihydrotyrosine. The enzymatic products most plausibly on path to H(2)Phe illustrate the versatile metabolic rerouting of prephenate from aromatic amino acid synthesis to antibiotic synthesis.

Incorporation of L-2,5-dihydrophenylalanine into cell proteins of Escherichia coli and sarcoma 180

l-2,5-Dihydrophenylalanine is extensively incorporated as a phenylalanine analogue into cell proteins. Phenylalanine-requiring Escherichia coli ATCC 9723f and sarcoma 180 grow at normal rates initially with the analogue and maximally replace 65 and 33%, respectively, of phenylalanine in the peptide residues of their cell protein without death. With the analogue alone growth of E. coli becomes non-steady-state and asymptotically inhibited. In mixtures of the analogue and phenylalanine, growth eventually becomes steady state or logarithmic. The logarithmic rate is inversely proportional to the extent of incorporation of this analogue or of p-fluorophenylalanine, and the projected maximal replacement is the same as that obtained asymptotically with the analogue alone. Thus, the toxicities in steady-state and non-steady-state growth are closely related. Moreover, it is proposed that single salient protein defects may determine the extent of growth rate reduction.