title: The 60S associated ribosome biogenesis factor LSG1-2 is required for 40S maturation in Arabidopsis thaliana.
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.
authors.affiliation: Department of Biosciences, Goethe University, Molecular Cell Biology of Plants and Cluster of Excellence, Max von Laue Str. 9, 60438 Frankfurt/Main, Frankfurt, Germany.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Weis
authors.forename: Sandra
authors.initials: S
authors.lastname: Missbach
authors.forename: Julian
authors.initials: J
authors.lastname: Marzi
authors.forename: Markus T
authors.initials: MT
authors.lastname: Bohnsack
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C000602136:LSG1-2 protein, Arabidopsis; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D020558:GTP Phosphohydrolases
keywords: 60S maturation; Arabidopsis thaliana; LSG1; curled leaves; early plant development; nucleolus; rRNA processing; ribosome biogenesis