Target of Rapamycin regulates development and ribosomal RNA dxpression through Kinase domain in Arabidopsis

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DOIResolve DOI: http://doi.org/10.1104/pp.110.169045
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TypeArticle
Journal titlePlant Physiology
Volume155
Issue3
Pages13671382; # of pages: 16
AbstractTOR (Target Of Rapamycin) is a central regulator of cell growth, cell death, nutrition, starvation, hormone and stress responses in diverse eukaryotes. However, very little is known about TOR signaling and the associated functional domains in plants. We have taken a genetic approach to dissect TOR functions in Arabidopsis (Arabidopsis thaliana) and report here that the kinase domain is essential for the role of TOR in embryogenesis and 45S rRNA expression. Twelve new T-DNA insertion mutants, spanning 14.2 kb of TOR encoding genomic region, have been characterized. Nine of these share expression of defective kinase domain and embryo arrest at 16-32 cell stage. However, three T-DNA insertion lines affecting FATC domain displayed normal embryo development, indicating that FATC domain was dispensable in Arabidopsis. Genetic complementation showed that the TOR kinase domain alone in tor-10/tor-10 mutant background can rescue early embryo lethality and restore normal development. Over-expression of full-length TOR or kinase domain in Arabidopsis displayed developmental abnormalities in meristem, leaf, root, stem, flowering time and senescence. We further show that TOR, especially the kinase domain, plays a role in ribosome biogenesis by activating 45S rRNA production. Of the six putative nuclear localization sequences in the kinase domain, NLS6 was identified to confer TOR nuclear targeting in transient expression assays. Chromatin immunoprecipitation studies revealed that the HEAT repeat domain binds to 45S rRNA promoter and the 5’ETS (external transcribed spacer elements) motif. Together, these results show that TOR controls the embryogenesis, postembryonic development and 45S rRNA production through its kinase domain in Arabidopsis.
Publication date
LanguageEnglish
AffiliationNRC Genomics and Health Initiative; NRC Plant Biotechnology Institute; National Research Council Canada
Peer reviewedYes
NRC number50164
NPARC number18749437
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Record identifier636d3a9f-2a04-45cc-ba4b-28785c088747
Record created2012-03-30
Record modified2016-05-09
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