title: A rice chloroplast transit peptide sequence does not alter the cytoplasmic localization of sheep serotonin N-acetyltransferase expressed in transgenic rice plants.
abstract: Ectopic overexpression of melatonin biosynthetic genes of animal origin has been used to generate melatonin-rich transgenic plants to examine the functional roles of melatonin in plants. However, the subcellular localization of these proteins expressed in the transgenic plants remains unknown. We studied the localization of sheep (Ovis aries) serotonin N-acetyltransferase (OaSNAT) and a translational fusion of a rice SNAT transit peptide to OaSNAT (TS:OaSNAT) in plants. Laser confocal microscopy analysis revealed that both OaSNAT and TS:OaSNAT proteins were localized to the cytoplasm even with the addition of the transit sequence to OaSNAT. Transgenic rice plants overexpressing the TS:OaSNAT fusion transgene exhibited high SNAT enzyme activity relative to untransformed wild-type plants, but lower activity than transgenic rice plants expressing the wild-type OaSNAT gene. Melatonin levels in both types of transgenic rice plant corresponded well with SNAT enzyme activity levels. The TS:OaSNAT transgenic lines exhibited increased seminal root growth relative to wild-type plants, but less than in the OaSNAT transgenic lines, confirming that melatonin promotes root growth. Seed-specific OaSNAT expression under the control of a rice prolamin promoter did not confer high levels of melatonin production in transgenic rice seeds compared with seeds from transgenic plants expressing OaSNAT under the control of the constitutive maize ubiquitin promoter.
authors.affiliation: Department of Biotechnology, Bioenergy Research Center, Chonnam National University, Gwangju, Korea.
authors.forename: Yeong
authors.initials: Y
authors.lastname: Byeon
authors.forename: Hyoung Yool
authors.initials: HY
authors.lastname: Lee
authors.forename: Kyungjin
authors.initials: K
authors.lastname: Lee
authors.forename: Kyoungwhan
authors.initials: K
authors.lastname: Back
mesh_terms: D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D060365:Chloroplast Proteins / Q000737:chemistry* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006540:Herbicides / Q000494:pharmacology; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology; D008550:Melatonin / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D021382:Protein Sorting Signals; D011743:Pyrimidines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D012756:Sheep
chemical_list: D060365:Chloroplast Proteins; D006540:Herbicides; D006845:Hydrocarbons, Fluorinated; D021382:Protein Sorting Signals; D011743:Pyrimidines; C078737:chloroplast transit peptides; C487162:butafenacil; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin
keywords: melatonin; prolamin promoter; rice seedlings; serotonin N-acetyltransferase; subcellular localization; transgenic rice