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Bousquet L, Hemon C, Malburet P, Bucchini F, Vandepoele K, Grimsley N, Moreau H, Echeverria M. The medium-size noncoding RNA transcriptome of Ostreococcus tauri, the smallest living eukaryote, reveals a large family of small nucleolar RNAs displaying multiple genomic expression strategies. NAR Genom Bioinform 2020; 2:lqaa080. [PMID: 33575626 PMCID: PMC7671301 DOI: 10.1093/nargab/lqaa080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/31/2020] [Accepted: 09/17/2020] [Indexed: 11/14/2022] Open
Abstract
The small nucleolar RNAs (snoRNAs), essential for ribosome biogenesis, constitute a major family of medium-size noncoding RNAs (mncRNAs) in all eukaryotes. We present here, for the first time in a marine unicellular alga, the characterization of the snoRNAs family in Ostreococcus tauri, the smallest photosynthetic eukaryote. Using a transcriptomic approach, we identified 131 O. tauri snoRNAs (Ot–snoRNA) distributed in three classes: the C/D snoRNAs, the H/ACA snoRNAs and the MRP RNA. Their genomic organization revealed a unique combination of both the intronic organization of animals and the polycistronic organization of plants. Remarkably, clustered genes produced Ot–snoRNAs with unusual structures never previously described in plants. Their abundances, based on quantification of reads and northern blots, showed extreme differences in Ot–snoRNA accumulation, mainly determined by their differential stability. Most of these Ot–snoRNAs were predicted to target rRNAs or snRNAs. Seventeen others were orphan Ot–snoRNAs that would not target rRNA. These were specific to O. tauri or Mamiellophyceae and could have functions unrelated to ribosome biogenesis. Overall, these data reveal an ‘evolutionary response’ adapted to the extreme compactness of the O. tauri genome that accommodates the essential Ot–snoRNAs, developing multiple strategies to optimize their coordinated expression with a minimal cost on regulatory circuits.
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Affiliation(s)
- Laurie Bousquet
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Claire Hemon
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Paul Malburet
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - François Bucchini
- Department of Plant Systems Biology,VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
| | - Klaas Vandepoele
- Department of Plant Systems Biology,VIB, 9052 Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium
- Bioinformatic Institute Ghent, Ghent University, 9052 Ghent, Belgium
| | - Nigel Grimsley
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Hervé Moreau
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
| | - Manuel Echeverria
- Sorbonne Université, CNRS, Laboratoire de Biologie Intégrative des Organismes Marins , UMR7232, F-66650 Banyuls sur Mer, France
- Département de Biologie, Université de Perpignan via Domitia, 66860 Perpignan Cedex, France
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