title: ERIL1, the plant homologue of ERI-1, is involved in the processing of chloroplastic rRNAs.
abstract: Proteins belonging to the enhancer of RNA interference-1 subfamily of 3'-5' exoribonucleases participate in divergent RNA pathways. They degrade small interfering RNAs (siRNAs), thus suppressing RNA interference, and are involved in the maturation of ribosomal RNAs and the degradation of histone messenger RNAs (mRNAs). Here, we report evidence for the role of the plant homologue of these proteins, which we termed ENHANCED RNA INTERFERENCE-1-LIKE-1 (ERIL1), in chloroplast function. In vitro assays with AtERIL1 proved that the conserved 3'-5' exonuclease activity is shared among all homologues studied. Confocal microscopy revealed that ERL1, a nucleus-encoded protein, is targeted to the chloroplast. To gain insight into its role in plants, we used Nicotiana benthamiana and Arabidopsis thaliana plants that constitutively overexpress or suppress ERIL1. In the mutant lines of both species we observed malfunctions in photosynthetic ability. Molecular analysis showed that ERIL1 participates in the processing of chloroplastic ribosomal RNAs (rRNAs). Lastly, our results suggest that the missexpression of ERIL1 may have an indirect effect on the microRNA (miRNA) pathway. Altogether our data point to an additional piece of the puzzle in the complex RNA metabolism of chloroplasts.
authors.affiliation: Department of Biology, University of Crete, Vassilika Vouton, Heraklion/Crete, GR-71409, Greece.|Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion/Crete, GR-71110, Greece.
authors.forename: Glykeria
authors.initials: G
authors.lastname: Mermigka
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion/Crete, GR-71110, Greece.
authors.forename: Jutta Maria
authors.initials: JM
authors.lastname: Helm
authors.affiliation: Department of Biology, University of Crete, Vassilika Vouton, Heraklion/Crete, GR-71409, Greece.|Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion/Crete, GR-71110, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vlatakis
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion/Crete, GR-71110, Greece.
authors.forename: Heiko Tobias
authors.initials: HT
authors.lastname: Schumacher
authors.affiliation: Department of Biology, University of Crete, Vassilika Vouton, Heraklion/Crete, GR-71409, Greece.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Vamvaka
authors.affiliation: Department of Biology, University of Crete, Vassilika Vouton, Heraklion/Crete, GR-71409, Greece.|Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion/Crete, GR-71110, Greece.
authors.forename: Kriton
authors.initials: K
authors.lastname: Kalantidis
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D034622:RNA Interference; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D012335:RNA, Ribosomal; D034741:RNA, Small Interfering; D005095:Exoribonucleases
keywords: 
  Arabidopsis thaliana
  ; 
  Nicotiana benthamiana
  ; RNA silencing; chloroplast; enhanced RNA interference-1; exoribonuclease