OTP70 is a pentatricopeptide repeat protein of the E subgroup involved in splicing of the plastid transcript rpoC1

Authors

  • Anne-Laure Chateigner-Boutin,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
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    • Present address: UR1268 Biopolymères, Interactions, Assemblages, INRA, F-44316 Nantes, France.

  • Catherine Colas des Francs-Small,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
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  • Etienne Delannoy,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
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    • Present address: URGV (Unité de Recherche en Génomique Végétale), UMR INRA 1165 – Université UEVE (Evry), 2, rue Gaston Crémieux – CP 5708, 91057 Évry Cedex, France.

  • Sabine Kahlau,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
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  • Sandra K. Tanz,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
    2. Centre of Excellence in Computational Systems Biology, University of Western Australia, Crawley 6009 WA, Australia
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  • Andéol Falcon de Longevialle,

    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
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    • Present address: URGV (Unité de Recherche en Génomique Végétale), UMR INRA 1165 – Université UEVE (Evry), 2, rue Gaston Crémieux – CP 5708, 91057 Évry Cedex, France.

  • Sota Fujii,

    1. Centre of Excellence in Computational Systems Biology, University of Western Australia, Crawley 6009 WA, Australia
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  • Ian Small

    Corresponding author
    1. Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia
    2. Centre of Excellence in Computational Systems Biology, University of Western Australia, Crawley 6009 WA, Australia
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(fax +61 8 6488 4401; e-mail ian.small@uwa.edu.au).

Summary

Over 20 proteins of the pentatricopeptide repeat (PPR) family have been demonstrated to be involved in RNA editing in plant mitochondria and chloroplasts. All of these editing factors contain a so-called ‘E’ domain that has been shown to be essential for editing to occur. The presumption has been that this domain recruits the (unknown) editing enzyme to the RNA. In this report, we show that not all putative E-class PPR proteins are directly involved in RNA editing. Disruption of the OTP70 gene leads to a strong defect in splicing of the plastid transcript rpoC1, leading to a virescent phenotype. The mutant has a chloroplast transcript pattern characteristic of a reduction in plastid-encoded RNA polymerase activity. The E domain of OTP70 is not required for splicing, and can be deleted or replaced by the E domain from the known editing factor CRR4 without loss of rpoC1 splicing. Furthermore, the E domain of OTP70 is incapable of inducing RNA editing when fused to the RNA binding domain of CRR4. We conclude that the truncated E domain of OTP70 is no longer functional in RNA editing, and that the protein has acquired a new function in promoting RNA splicing.

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