title: SOT1, a pentatricopeptide repeat protein with a small MutS-related domain, is required for correct processing of plastid 23S-4.5S rRNA precursors in Arabidopsis thaliana.
abstract: Ribosomal RNA processing is essential for plastid ribosome biogenesis, but is still poorly understood in higher plants. Here, we show that SUPPRESSOR OF THYLAKOID FORMATION1 (SOT1), a plastid-localized pentatricopeptide repeat (PPR) protein with a small MutS-related domain, is required for maturation of the 23S-4.5S rRNA dicistron. Loss of SOT1 function leads to slower chloroplast development, suppression of leaf variegation, and abnormal 23S and 4.5S processing. Predictions based on the PPR motif sequences identified the 5' end of the 23S-4.5S rRNA dicistronic precursor as a putative SOT1 binding site. This was confirmed by electrophoretic mobility shift assay, and by loss of the abundant small RNA 'footprint' associated with this site in sot1 mutants. We found that more than half of the 23S-4.5S rRNA dicistrons in sot1 mutants contain eroded and/or unprocessed 5' and 3' ends, and that the endonucleolytic cleavage product normally released from the 5' end of the precursor is absent in a sot1 null mutant. We postulate that SOT1 binding protects the 5' extremity of the 23S-4.5S rRNA dicistron from exonucleolytic attack, and favours formation of the RNA structure that allows endonucleolytic processing of its 5' and 3' ends.
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Wu
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Sheng
authors.initials: S
authors.lastname: Liu
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Hannes
authors.initials: H
authors.lastname: Ruwe
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Delin
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Joanna
authors.initials: J
authors.lastname: Melonek
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Xupeng
authors.initials: X
authors.lastname: Hu
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Gusewski
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, National Centre of Plant Gene Research, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Yin
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.|Centre of Excellence in Computational Systems Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Small
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.
authors.forename: Katharine A
authors.initials: KA
authors.lastname: Howell
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Jirong
authors.initials: J
authors.lastname: Huang
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D030821:Plants, Genetically Modified; D018087:Plastids / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid
chemical_list: D029681:Arabidopsis Proteins; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012338:RNA, Ribosomal, 23S; C538752:pentatricopeptide repeat protein, Arabidopsis
keywords: Arabidopsis thaliana; chloroplast; pentatricopeptide repeat protein; plastid ribosome; ribosomal RNA; small MutS-related domain