title: RNA Recognition Motif-Containing Protein ORRM4 Broadly Affects Mitochondrial RNA Editing and Impacts Plant Development and Flowering.
abstract: Plant RNA editosomes modify cytidines (C) to uridines (U) at specific sites in plastid and mitochondrial transcripts. Members of the RNA-editing factor interacting protein (RIP) family and Organelle RNA Recognition Motif-containing (ORRM) family are essential components of the Arabidopsis (Arabidopsis thaliana) editosome. ORRM2 and ORRM3 have been recently identified as minor mitochondrial editing factors whose silencing reduces editing efficiency at ∼6% of the mitochondrial C targets. Here we report the identification of ORRM4 (for organelle RRM protein 4) as a novel, major mitochondrial editing factor that controls ∼44% of the mitochondrial editing sites. C-to-U conversion is reduced, but not eliminated completely, at the affected sites. The orrm4 mutant exhibits slower growth and delayed flowering time. ORRM4 affects editing in a site-specific way, though orrm4 mutation affects editing of the entire transcript of certain genes. ORRM4 contains an RRM domain at the N terminus and a Gly-rich domain at the C terminus. The RRM domain provides the editing activity of ORRM4, whereas the Gly-rich domain is required for its interaction with ORRM3 and with itself. The presence of ORRM4 in the editosome is further supported by its interaction with RIP1 in a bimolecular fluorescence complementation assay. The identification of ORRM4 as a major mitochondrial editing factor further expands our knowledge of the composition of the RNA editosome and reveals that adequate mitochondrial editing is necessary for normal plant development.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853 (X.S., A.G., M.R.H., S.B.).
authors.forename: Xiaowen
authors.identifier: http://orcid.org/0000-0003-0281-2953
authors.initials: X
authors.lastname: Shi
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853 (X.S., A.G., M.R.H., S.B.).
authors.forename: Arnaud
authors.initials: A
authors.lastname: Germain
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853 (X.S., A.G., M.R.H., S.B.) mrh5@cornell.edu.
authors.forename: Maureen R
authors.identifier: http://orcid.org/0000-0001-8141-3058
authors.initials: MR
authors.lastname: Hanson
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853 (X.S., A.G., M.R.H., S.B.).
authors.forename: Stéphane
authors.identifier: http://orcid.org/0000-0003-2805-7298
authors.initials: S
authors.lastname: Bentolila
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008928:Mitochondria / Q000235:genetics; D009154:Mutation; D059372:Nucleotide Motifs; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary / Q000235:genetics; D012313:RNA / Q000235:genetics*; D017393:RNA Editing; D000077278:RNA, Mitochondrial; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C000610872:ORRM4 protein, Arabidopsis; C574455:RIP1 protein, Arabidopsis; D000077278:RNA, Mitochondrial; D016601:RNA-Binding Proteins; D012313:RNA