title: Silencing of NbBTF3 results in developmental defects and disturbed gene expression in chloroplasts and mitochondria of higher plants.
abstract: BTF3 (betaNAC) was originally isolated as a general transcription factor required for RNA polymerase II-dependent transcription, and later found to be a beta-subunit of nascent-polypeptide-associated complex that has been implicated in regulating protein localization during translation. In this study, virus-induced gene silencing of NbBTF3 encoding a Nicotiana benthamiana homolog of human BTF3 caused leaf yellowing and abnormal leaf morphology without altering the overall growth of the plant. The NbBTF3 gene is constitutively expressed and the NbBTF3-GFP fusion protein is primarily targeted to the nucleus. At the cellular level, downregulation of NbBTF3 expression reduced the chloroplast sizes and chlorophyll contents. The affected cells produced excessive amounts of reactive oxygen species. Furthermore, the transcript level of various plastid- and mitochondria-encoded genes was severely reduced in the NbBTF3-depleted leaf cells. These findings indicate that depletion of NbBTF3 activity preferentially affected development and/or physiology of chloroplasts and mitochondria in plants, possibly by hampering efficient translocation of the nascent organellar proteins into the organelles.
authors.affiliation: Laboratory of Plant Genomics, Korea Research Institute of Bioscience and Biotechnology, Taejon, 305-333, South Korea.
authors.forename: Kyoung-Sil
authors.initials: KS
authors.lastname: Yang
authors.forename: Hee-Seung
authors.initials: HS
authors.lastname: Kim
authors.forename: Un-Ho
authors.initials: UH
authors.lastname: Jin
authors.forename: Sang Sook
authors.initials: SS
authors.lastname: Lee
authors.forename: Jong-A
authors.initials: JA
authors.lastname: Park
authors.forename: Yong Pyo
authors.initials: YP
authors.lastname: Lim
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Pai
mesh_terms: D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014026:Nicotiana / Q000166:cytology* / Q000235:genetics*; D014157:Transcription Factors / Q000737:chemistry / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C063552:transcription factor BTF3