title: Identification of a plastidial phenylalanine exporter that influences flux distribution through the phenylalanine biosynthetic network.
abstract: In addition to proteins, L-phenylalanine is a versatile precursor for thousands of plant metabolites. Production of phenylalanine-derived compounds is a complex multi-compartmental process using phenylalanine synthesized predominantly in plastids as precursor. The transporter(s) exporting phenylalanine from plastids, however, remains unknown. Here, a gene encoding a Petunia hybrida plastidial cationic amino-acid transporter (PhpCAT) functioning in plastidial phenylalanine export is identified based on homology to an Escherichia coli phenylalanine transporter and co-expression with phenylalanine metabolic genes. Radiolabel transport assays show that PhpCAT exports all three aromatic amino acids. PhpCAT downregulation and overexpression result in decreased and increased levels, respectively, of phenylalanine-derived volatiles, as well as phenylalanine, tyrosine and their biosynthetic intermediates. Metabolic flux analysis reveals that flux through the plastidial phenylalanine biosynthetic pathway is reduced in PhpCAT RNAi lines, suggesting that the rate of phenylalanine export from plastids contributes to regulating flux through the aromatic amino-acid network.
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Widhalm
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, Indiana 47907-2010, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Gutensohn
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.|Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, Indiana 47907-2010, USA.
authors.forename: Heejin
authors.initials: H
authors.lastname: Yoo
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.
authors.forename: Funmilayo
authors.initials: F
authors.lastname: Adebesin
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.|Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, Indiana 47907-2010, USA.
authors.forename: Yichun
authors.initials: Y
authors.lastname: Qian
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.
authors.forename: Longyun
authors.initials: L
authors.lastname: Guo
authors.affiliation: School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr, West Lafayette, Indiana 47907-2100, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Jaini
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Lynch
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: McCoy
authors.affiliation: Bioinformatics Core, Purdue University, 155 South Grant Street, West Lafayette, Indiana 47907, USA.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Shreve
authors.affiliation: Bioinformatics Core, Purdue University, 155 South Grant Street, West Lafayette, Indiana 47907, USA.
authors.forename: Jyothi
authors.initials: J
authors.lastname: Thimmapuram
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, Indiana 47907-2010, USA.
authors.forename: David
authors.initials: D
authors.lastname: Rhodes
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.|School of Chemical Engineering, Purdue University, 480 Stadium Mall Dr, West Lafayette, Indiana 47907-2100, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Morgan
authors.affiliation: Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, Indiana 47907-2063, USA.|Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Dr, West Lafayette, Indiana 47907-2010, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Dudareva
mesh_terms: D026923:Amino Acid Transport Systems, Basic / Q000378:metabolism*; D053898:Biosynthetic Pathways; D004926:Escherichia coli; D064688:Metabolic Flux Analysis; D032306:Petunia; D010649:Phenylalanine / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000378:metabolism*; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D014443:Tyrosine / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000378:metabolism
chemical_list: D026923:Amino Acid Transport Systems, Basic; D010940:Plant Proteins; D055549:Volatile Organic Compounds; D014443:Tyrosine; D010649:Phenylalanine