title: Identification of enzymes for adenosine-to-inosine editing and discovery of cytidine-to-uridine editing in nucleus-encoded transfer RNAs of Arabidopsis.
abstract: In all organisms, transfer RNAs (tRNAs) contain numerous modified nucleotides. For many base modifications in tRNAs, the functional significance is not well understood, and the enzymes performing the modification reactions are unknown. Here, we have studied members of a family of putative nucleotide deaminases in the model plant Arabidopsis (Arabidopsis thaliana). We show that two Arabidopsis genes encoding homologs of yeast (Saccharomyces cerevisiae) tRNA adenosine deaminases catalyze adenosine-to-inosine editing in position 34 of several cytosolic tRNA species. The encoded proteins (AtTAD2 and AtTAD3, for tRNA-specific adenosine deaminase) localize to the nucleus and interact with each other in planta in bimolecular fluorescence complementation and coimmunoprecipitation assays. Both AtTAD2 and AtTAD3 are encoded by essential genes whose knockout is lethal and leads to arrested embryo development at the globular stage. Knockdown mutants for AtTAD2 and AtTAD3 display reduced growth and inefficient editing from adenosine to inosine in six nucleus-encoded tRNA species. Moreover, upon comparison of DNA and complementary DNA sequences, we discovered cytidine-to-uridine RNA editing in position 32 of two nucleus-encoded serine tRNAs, tRNA-serine(AGA) and tRNA-serine(GCT). This adds a unique type of RNA editing to the modifications occurring in nuclear genome-encoded RNAs in plants.
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Karcher
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany rbock@mpimp-golm.mpg.de.
authors.forename: Ralph
authors.identifier: http://orcid.org/0000-0001-7502-6940
authors.initials: R
authors.lastname: Bock
mesh_terms: D000241:Adenosine / Q000235:genetics; D000243:Adenosine Deaminase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics; D003562:Cytidine / Q000235:genetics; D003600:Cytosol; D020043:Genes, Essential / Q000235:genetics; D017930:Genes, Reporter; D007288:Inosine / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D017393:RNA Editing / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014529:Uridine / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D018749:RNA, Plant; D007288:Inosine; D003562:Cytidine; D012343:RNA, Transfer; D000243:Adenosine Deaminase; C000604137:TAD2 protein, Arabidopsis; C000604138:TAD3 protein, Arabidopsis; D000241:Adenosine; D014529:Uridine