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J Exp Bot. 2015 Oct;66(20):6297-310. doi: 10.1093/jxb/erv337. Epub 2015 Jul 10.

The nucleolar GTPase nucleostemin-like 1 plays a role in plant growth and senescence by modulating ribosome biogenesis.

Author information

1
Department of Systems Biology, Yonsei University, Seoul 120-749, Korea.
2
Department of Plant Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, Korea.
3
Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea.
4
Department of Systems Biology, Yonsei University, Seoul 120-749, Korea hspai@yonsei.ac.kr.

Abstract

Nucleostemin is a nucleolar GTP-binding protein that is involved in stem cell proliferation, embryonic development, and ribosome biogenesis in mammals. Plant nucleostemin-like 1 (NSN1) plays a role in embryogenesis, and apical and floral meristem development. In this study, a nucleolar function of NSN1 in the regulation of ribosome biogenesis was identified. Green fluorescent protein (GFP)-fused NSN1 localized to the nucleolus, which was primarily determined by its N-terminal domain. Recombinant NSN1 and its N-terminal domain (NSN1-N) bound to RNA in vitro. Recombinant NSN1 expressed GTPase activity in vitro. NSN1 silencing in Arabidopsis thaliana and Nicotiana benthamiana led to growth retardation and premature senescence. NSN1 interacted with Pescadillo and EBNA1 binding protein 2 (EBP2), which are nucleolar proteins involved in ribosome biogenesis, and with several ribosomal proteins. NSN1, NSN1-N, and EBP2 co-fractionated primarily with the 60S ribosomal large subunit in vivo. Depletion of NSN1 delayed 25S rRNA maturation and biogenesis of the 60S ribosome subunit, and repressed global translation. NSN1-deficient plants exhibited premature leaf senescence, excessive accumulation of reactive oxygen species, and senescence-related gene expression. Taken together, these results suggest that NSN1 plays a crucial role in plant growth and senescence by modulating ribosome biogenesis.

KEYWORDS:

Delayed 25S rRNA maturation; GTPase activity; RNA binding activity; nucleolar localization; premature senescence; suppressed translation.

PMID:
26163696
PMCID:
PMC4588883
DOI:
10.1093/jxb/erv337
[Indexed for MEDLINE]
Free PMC Article

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