miRNAs control gene expression in the single-cell alga Chlamydomonas reinhardtii

Attila Molnar, Frank Schwach, David J. Studholme, Eva C. Thuenemann, David C. Baulcombe*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

MicroRNAs (miRNAs) in eukaryotes guide post-transcriptional regulation by means of targeted RNA degradation and translational arrest(1). They are released by a Dicer nuclease as a 21-24-nucleotide RNA duplex from a precursor in which an imperfectly matched inverted repeat forms a partly double-stranded region. One of the two strands is then recruited by an Argonaute nuclease that is the effector protein of the silencing mechanism. Short interfering RNAs (siRNAs), which are similar to miRNAs, are also produced by Dicer but the precursors are perfectly double-stranded RNA. These siRNAs guide post-transcriptional regulation, as with miRNAs, and epigenetic genome modification. Diverse eukaryotes including fungi, plants, protozoans and metazoans produce siRNAs(2-5) but, until now, miRNAs have not been described in unicellular organisms and it has been suggested that they evolved together with multicellularity in separate plant and animal lineages(6). Here we show that the unicellular alga Chlamydomonas reinhardtii contains miRNAs, putative evolutionary precursors of miRNAs and species of siRNAs resembling those in higher plants. The common features of miRNAs and siRNAs in an alga and in higher plants indicate that complex RNA-silencing systems evolved before multicellularity and were a feature of primitive eukaryotic cells.

Original languageEnglish
Pages (from-to)1126-U15
Number of pages5
JournalNature
Volume447
Issue number7148
DOIs
Publication statusPublished - 28 Jun 2007

Keywords

  • TRANS-ACTING SIRNAS
  • SMALL RNAS
  • INTERFERING RNAS
  • ARABIDOPSIS
  • MICRORNAS
  • SEQUENCES
  • PLANTS
  • METHYLATION
  • BIOGENESIS
  • CLONING

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