title: Analysis of barley chloroplast psbD light-responsive promoter elements in transplastomic tobacco.
abstract: The plastid gene psbD encodes D2, a photosystem II reaction center chlorophyll-binding protein. psbD is transcribed from a conserved chloroplast promoter that is activated by blue, white, or UV-A light. In this study, various forms of the barley (Hordeum vulgare L.) chloroplast psbD-LRP were fused to the uidA reporter gene and introduced into the tobacco (Nicotiana tabacum L.) plastid genome through homologous recombination. Primer extension analysis of transcripts from the psbD-LRP-uidA construct showed that the barley psbD-LRP was activated in tobacco by blue or white light. Transcription from this construct was also regulated by circadian cycling indicating that the barley psbD-LRP could respond to light modulated regulatory pathways in tobacco. Mutation of the psbD-LRP prokaryotic -10 promoter element reduced transcription to very low levels in all light regimes. In contrast, mutation of a prokaryotic -35 promoter element had no effect on transcription from the psbD-LRP. Deletion or mutation of an upstream activating element, the AAG-box (-36 to -64), also reduced transcription from the construct to very low levels. In contrast, deletion of the upstream PGT-box (-71 to -100) did not alter promoter activation by blue light, or responsiveness to circadian cycling. These in vivo studies confirm the importance of the psbD-LRP -10 promoter element and AAG-box in light regulation and demonstrate that these elements are sufficient to mediate circadian cycling of the barley psbD promoter.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Thum
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.forename: D T
authors.initials: DT
authors.lastname: Morishige
authors.forename: C
authors.initials: C
authors.lastname: Eibl
authors.forename: H U
authors.initials: HU
authors.lastname: Koop
authors.forename: J E
authors.initials: JE
authors.lastname: Mullet
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002940:Circadian Rhythm; D018742:DNA, Chloroplast / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005966:Glucuronidase / Q000235:genetics; D001467:Hordeum / Q000235:genetics*; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D045332:Photosystem II Protein Complex; D030821:Plants, Genetically Modified / Q000235:genetics / Q000528:radiation effects; D010947:Plants, Toxic; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D016415:Sequence Alignment; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D014026:Nicotiana / Q000235:genetics* / Q000528:radiation effects; D014158:Transcription, Genetic
chemical_list: D018742:DNA, Chloroplast; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011993:Recombinant Fusion Proteins; D005966:Glucuronidase