Xenopus germline nanos1 is translationally repressed by a novel structure-based mechanism

Xueting Luo, Steve Nerlick, Weijun An, Mary Lou King

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


The translational repressor Nanos is expressed in the germline and stem cell populations of jellyfish as well as humans. Surprisingly, we observed that unlike other mRNAs, synthetic nanos1 RNA translates very poorly if at all after injection into Xenopus oocytes. The current model of simple sequestration of nanos1 within germinal granules is insufficient to explain this observation and suggests that a second level of repression must be operating. We find that an RNA secondary structural element immediately downstream of the AUG start site is both necessary and sufficient to prevent ribosome scanning in the absence of a repressor. Accordingly, repression is relieved by small in-frame insertions before this secondary structure, or translational control element (TCE), that provide the 15 nucleotides required for ribosome entry. nanos1 is translated shortly after fertilization, pointing to the existence of a developmentally regulated activator. Oocyte extracts were rendered fully competent for nanos1 translation after the addition of a small amount of embryo extract, confirming the presence of an activator. Misexpression of Nanos1 in oocytes from unlocalized RNA results in abnormal development, highlighting the importance of TCE-mediated translational repression. Although found in prokaryotes, steric hindrance as a mechanism for negatively regulating translation is novel for a eukaryotic RNA. These observations unravel a new mode of nanos1 regulation at the post-transcriptional level that is essential for normal development.

Original languageEnglish (US)
Pages (from-to)589-598
Number of pages10
Issue number3
StatePublished - Feb 1 2011
Externally publishedYes


  • Germline
  • Nanos family
  • RNA secondary structure
  • Translational repression
  • Xenopus

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology


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