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

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

Author information

1
Department of Biosciences, Goethe University, Molecular Cell Biology of Plants and Cluster of Excellence, Max von Laue Str. 9, 60438 Frankfurt/Main, Frankfurt, Germany.

Abstract

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

PMID:
25319368
DOI:
10.1111/tpj.12703
[Indexed for MEDLINE]
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