title: PRBP plays a role in plastid ribosomal RNA maturation and chloroplast biogenesis in Nicotiana benthamiana.
abstract: In the present study, we investigated protein characteristics and physiological functions of PRBP (plastid RNA-binding protein) in Nicotiana benthamiana. PRBP fused to green fluorescent protein (GFP) localized to the chloroplasts. Recombinant PRBP proteins bind to single-stranded RNA in vitro, but not to DNA in a double- or a single-stranded form. Virus-induced gene silencing (VIGS) of PRBP resulted in leaf yellowing in N. benthamiana. At the cellular level, PRBP depletion disrupted chloroplast biogenesis: chloroplast number and size were reduced, and the thylakoid membrane was poorly developed. In PRBP-silenced leaves, protein levels of plastid-encoded genes were significantly reduced, whereas their mRNA levels were normal regardless of their promoter types indicating that PRBP deficiency primarily affects translational or post-translational processes. Depletion of PRBP impaired processing of the plastid-encoded 4.5S ribosomal RNA, resulting in accumulation of the larger precursor rRNAs in the chloroplasts. In addition, PRBP-deficient chloroplasts contained significantly reduced levels of mature 4.5S and 5S rRNAs in the polysomal fractions, indicating decreased chloroplast translation. These results suggest that PRBP plays a role in chloroplast rRNA processing and chloroplast development in higher plants.
authors.affiliation: Department of Biology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Yong-Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Hui-Kyung
authors.initials: HK
authors.lastname: Cho
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Jung
authors.forename: Chang Sook
authors.initials: CS
authors.lastname: Ahn
authors.forename: Hunseung
authors.initials: H
authors.lastname: Kang
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Pai
mesh_terms: D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D049452:Green Fluorescent Proteins / Q000032:analysis; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018087:Plastids / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D020524:Thylakoids / Q000502:physiology; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins