Decoding the Function of Expansion Segments in Ribosomes

Kotaro Fujii, Teodorus Theo Susanto, Saumya Saurabh, Maria Barna

Research output: Contribution to journalArticlepeer-review


Expansion segments (ESs) are enigmatic insertions within the eukaryotic ribosome, the longest of which resemble tentacle-like extensions that vary in length and sequence across evolution, with a largely unknown function. By selectively engineering rRNA in yeast, we find that one of the largest ESs, ES27L, has an unexpected function in translation fidelity. Ribosomes harboring a deletion in the distal portion of ES27L have increased amino acid misincorporation, as well as readthrough and frameshifting errors. By employing quantitative mass spectrometry, we further find that ES27L acts as an RNA scaffold to facilitate binding of a conserved enzyme, methionine amino peptidase (MetAP). We show that MetAP unexpectedly controls the accuracy of ribosome decoding, which is coupled to an increase in its enzymatic function through its interaction with ES27L. These findings reveal that variable ESs of the ribosome serve important functional roles and act as platforms for the binding of proteins that modulate translation across evolution.

Original languageEnglish (US)
Pages (from-to)1013-1020.e6
JournalMolecular Cell
Issue number6
StatePublished - Dec 20 2018


  • ES
  • ES27L
  • MetAP
  • expansion segment
  • methionine amino peptidase
  • rRNA
  • ribosome
  • translation fidelity

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Decoding the Function of Expansion Segments in Ribosomes'. Together they form a unique fingerprint.

Cite this