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Viola S, Cavaiuolo M, Drapier D, Eberhard S, Vallon O, Wollman FA, Choquet Y. MDA1, a nucleus-encoded factor involved in the stabilization and processing of the atpA transcript in the chloroplast of Chlamydomonas. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:1033-1047. [PMID: 30809889 DOI: 10.1111/tpj.14300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/11/2019] [Accepted: 02/18/2019] [Indexed: 05/21/2023]
Abstract
In Chlamydomonas reinhardtii, chloroplast gene expression is tightly regulated post-transcriptionally by gene-specific trans-acting protein factors. Here, we report the molecular identification of an OctotricoPeptide Repeat (OPR) protein, MDA1, which governs the maturation and accumulation of the atpA transcript, encoding subunit α of the chloroplast ATP synthase. As does TDA1, another OPR protein required for the translation of the atpA mRNA, MDA1 targets the atpA 5'-untranslated region (UTR). Unexpectedly, it binds within a region of approximately 100 nt in the middle of the atpA 5'-UTR, at variance with the stabilization factors characterized so far, which bind to the 5'-end of their target mRNA to protect it from 5' → 3' exonucleases. It binds the same region as TDA1, with which it forms a high-molecular-weight complex that also comprises the atpA mRNA. This complex dissociates upon translation, promoting degradation of the atpA mRNA. We suggest that atpA transcripts, once translated, enter the degradation pathway because they cannot reassemble with MDA1 and TDA1, which preferentially bind to de novo transcribed mRNAs.
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Affiliation(s)
- Stefania Viola
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Marina Cavaiuolo
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Dominique Drapier
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Stephan Eberhard
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Olivier Vallon
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Francis-André Wollman
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Yves Choquet
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
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