Identification of a small protein domain present in all plant lineages that confers high prephenate dehydratase activity. (26th July 2016)

• Record Type: Journal Article
• Authors: El‐Azaz, Jorge; de la Torre, Fernando; Ávila, Concepción; Cánovas, Francisco M.
• Is Part Of: Plant journal. Volume 87:Number 2(2016:Jul.)
• Page Start: 215
• Page End: 229
• Publication Date: 2016-07-26
• Subjects: phenylalanine -- prephenate dehydratase -- phenylpyruvate -- chloroplast -- Saccharomyces cerevisiae -- Pinus pinaster; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.13195
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: l ‐Phenylalanine serves as a building block for the biosynthesis of proteins, but also as a precursor for a wide range of plant‐derived compounds essential for plants and animals. Plants can synthesize Phe within the plastids using arogenate as a precursor; however, an alternative pathway using phenylpyruvate as an intermediate, described for most microorganisms, has recently been proposed. The functionality of this pathway requires the existence of enzymes with prephenate dehydratase (PDT) activity (EC 4.2.1.51) in plants. Using phylogenetic studies, functional complementation assays in yeast and biochemical analysis, we have identified the enzymes displaying PDT activity in Pinus pinaster . Through sequence alignment comparisons and s ite‐directed mutagenesis we have identified a 22‐amino acid region conferring PDT activity (PAC domain) and a single Ala314 residue critical to trigger this activity. Our results demonstrate that all plant clades include PAC domain‐containing ADTs, suggesting that the PDT activity, and thus the ability to synthesize Phe using phenylpyruvate as an intermediate, has been preserved throughout the evolution of plants. Moreover, this pathway together with the arogenate pathway gives plants a broad and versatile capacity to synthesize Phe and its derived compounds. PAC domain‐containing enzymes are also present in green and red algae, and glaucophytes, the three emerging clades following the primary endosymbiont event resulting in the acquisition of plastids in eukaryotes. The evolutionary prokaryotic origin of this domain is discussed. Significance Statement: Phenylalanine is essential for protein synthesis and as a precursor for metabolites such as lignin and flavonoids. Phenylalanine is synthesized by the arogenate pathway or by an alternative pathway, well studied in microorganisms, the phenylpyruvate pathway. Here we use a conifer to characterize the phenylpyruvate pathway and demonstrate that a conserved 20 amino acid domain in prephenate dehydratase is required for enzyme activity.