RNA-binding protein DUS16 plays an essential role in primary miRNA processing in the unicellular alga Chlamydomonas reinhardtii

Tomohito Yamasaki, Masayuki Onishi, Eun Jeong Kim, Heriberto Cerutti, Takeshi Ohama

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Canonical microRNAs (miRNAs) are embedded in duplexed stem-loops in long precursor transcripts and are excised by sequential cleavage by DICER nuclease(s). In this miRNA biogenesis pathway, dsRNA-binding proteins play important roles in animals and plants by assisting DICER. However, these RNA-binding proteins are poorly characterized in unicellular organisms. Here we report that a unique RNA-binding protein, Dull slicer-16 (DUS16), plays an essential role in processing of primary-miRNA (pri-miRNA) transcripts in the unicellular green alga Chlamydomonas reinhardtii. In animals and plants, dsRNA-binding proteins involved in miRNA biogenesis harbor two or three dsRNA-binding domains (dsRBDs), whereas DUS16 contains one dsRBD and also an ssRNA-binding domain (RRM). The null mutant of DUS16 showed a drastic reduction in most miRNA species. Production of these miRNAs was complemented by expression of full-length DUS16, but the expression of RRM- or dsRBD-truncated DUS16 did not restore miRNA production. Furthermore, DUS16 is predominantly localized to the nucleus and associated with nascent (unspliced form) pri-miRNAs and the DICER-LIKE 3 protein. These results suggest that DUS16 recognizes pri-miRNA transcripts cotranscriptionally and promotes their processing into mature miRNAs as a component of a microprocessor complex. We propose that DUS16 is an essential factor for miRNA production in Chlamydomonas and, because DUS16 is functionally similar to the dsRNA-binding proteins involved in miRNA biogenesis in animals and land plants, our report provides insight into this mechanism in unicellular eukaryotes.

Original languageEnglish (US)
Pages (from-to)10720-10725
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number38
DOIs
Publication statusPublished - Sep 20 2016

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Keywords

  • Chlamydomonas
  • MicroRNA biogenesis
  • Mutagenesis
  • Small RNA-seq
  • dsRNA-binding protein

ASJC Scopus subject areas

  • General

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