title: Recruitment of a ribosomal release factor for light- and stress-dependent regulation of petB transcript stability in Arabidopsis chloroplasts.
abstract: Land plant genomes encode four functional ribosomal peptide chain release factors (Prf) of eubacterial origin, two (PrfA and PrfB homologs) for each endosymbiotic organelle. Formerly, we have shown that the Arabidopsis thaliana chloroplast-localized PrfB homolog, PrfB1, is required not only for termination of translation but also for stabilization of UGA stop codon-containing chloroplast transcripts. A previously undiscovered PrfB-like protein, PrfB3, is localized to the chloroplast stroma in a petB RNA-containing complex and found only in vascular plants. Highly conserved positions of introns unequivocally indicate that PrfB3 arose from a duplication of PrfB1. Notably, PrfB3 is lacking the two most important tripeptide motifs characteristic for all eubacterial and organellar PrfB homologs described so far: the stop codon recognition motif SPF and the catalytic center GGQ for peptidyl-tRNA hydrolysis. Complementation studies, as well as functional and molecular analyses of two allelic mutations in Arabidopsis, both of which lead to a specific deficiency of the cytochrome b₆f complex, revealed that PrfB3 is essentially required for photoautotrophic growth. Plastid transcript, polysome, and translation analyses indicate that PrfB3 has been recruited in vascular plants for light- and stress-dependent regulation of stability of 3' processed petB transcripts to adjust cytochrome b₆ levels.
authors.affiliation: Biozentrum der Ludwig-Maximilians-Universität, Plant Molecular Biology/Botany, 82152 Planegg-Martinsried, Germany.
authors.forename: Rhea
authors.initials: R
authors.lastname: Stoppel
authors.forename: Lina
authors.initials: L
authors.lastname: Lezhneva
authors.forename: Serena
authors.initials: S
authors.lastname: Schwenkert
authors.forename: Salar
authors.initials: S
authors.lastname: Torabi
authors.forename: Susanne
authors.initials: S
authors.lastname: Felder
authors.forename: Karin
authors.initials: K
authors.lastname: Meierhoff
authors.forename: Peter
authors.initials: P
authors.lastname: Westhoff
authors.forename: Jörg
authors.initials: J
authors.lastname: Meurer
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018388:Codon, Terminator / Q000378:metabolism; D045346:Cytochrome b6f Complex / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport; D018506:Gene Expression Regulation, Plant; D008027:Light; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D016601:RNA-Binding Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; D018388:Codon, Terminator; C104657:PetB protein, plant; D010940:Plant Proteins; C472144:PrfB protein, Arabidopsis; C570178:PrfB3 protein, Arabidopsis; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; D045346:Cytochrome b6f Complex