The 60S associated ribosome biogenesis factor LSG1-2 is required for 40S maturation in Arabidopsis thaliana

Plant J. 2014 Dec;80(6):1043-56. doi: 10.1111/tpj.12703. Epub 2014 Nov 13.


Ribosome biogenesis involves a large ensemble of trans-acting factors, which catalyse rRNA processing, ribosomal protein association and ribosomal subunit assembly. The circularly permuted GTPase Lsg1 is such a ribosome biogenesis factor, which is involved in maturation of the pre-60S ribosomal subunit in yeast. We identified two orthologues of Lsg1 in Arabidopsis thaliana. Both proteins differ in their C-terminus, which is highly charged in atLSG1-2 but missing in atLSG1-1. This C-terminus of atLSG1-2 contains a functional nuclear localization signal in a part of the protein that also targets atLSG1-2 to the nucleolus. Furthermore, only atLSG1-2 is physically associated with ribosomes suggesting its function in ribosome biogenesis. Homozygous T-DNA insertion lines are viable for both LSG1 orthologues. In plants lacking atLSG1-2 18S rRNA precursors accumulate and a 20S pre-rRNA is detected, while the amount of pre-rRNAs that lead to the 25S and 5.8S rRNA is not changed. Thus, our results suggest that pre-60S subunit maturation is important for the final steps of pre-40S maturation in plants. In addition, the lsg1-2 mutants show severe developmental defects, including triple cotyledons and upward curled leaves, which link ribosome biogenesis to early plant and leaf development.

Keywords: 60S maturation; Arabidopsis thaliana; LSG1; curled leaves; early plant development; nucleolus; rRNA processing; ribosome biogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Nucleolus / metabolism
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism
  • RNA Precursors / genetics
  • RNA Precursors / metabolism
  • RNA Processing, Post-Transcriptional*
  • RNA, Ribosomal / genetics
  • RNA, Ribosomal / metabolism*
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism*


  • Arabidopsis Proteins
  • LSG1-2 protein, Arabidopsis
  • RNA Precursors
  • RNA, Ribosomal
  • Ribosomal Proteins
  • GTP Phosphohydrolases