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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
The Plant Journal (2016)
  • Wenjuan Wu, Chinese Academy of Sciences
  • Sheng Liu, The University of Western Australia
  • Hannes Ruwe, Humboldt-University Berlin
  • Delin Zhang, Huazhong Agricultural University
  • Joanna Melonek, The University of Western Australia
  • Yajuan Zhu, Chinese Academy of Sciences
  • Xupeng Hu, Chinese Academy of Sciences
  • Sandra Gusewski, The University of Western Australia
  • Ping Yin, Huazhong Agricultural University
  • Ian Small, The University of Western Australia
  • Kate Howell, The University of Notre Dame Australia
  • Jirong Huang, Chinese Academy of Sciences
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 50 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 50 and 30 ends, and that the endonucleolytic cleavage product
normally released from the 50 end of the precursor is absent in a sot1 null mutant. We postulate that SOT1
binding protects the 50 extremity of the 23S–4.5S rRNA dicistron from exonucleolytic attack, and favours formation
of the RNA structure that allows endonucleolytic processing of its 50 and 30 ends.
Disciplines
Publication Date
2016
DOI
10.1111/tpj.13126
Citation Information
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. Plant J 85(5): 607