Plant growth: the translational connection

Robaglia, Christophe; Menand, Benoît; Lei, Yang; Sormani, Rodnay; Nicolaı̈, Maryse; Géry, Carine; Téoulé, Evelyne; Deprost, Dorothée; Meyer, Christian

doi:10.1042/bst0320581

Cited by 24 publications

(28 citation statements)

References 23 publications

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“…Both cDNA sequences were confirmed to be identical to the GenBank annotation, and the TOR cDNA sequence was also found to be identical to the one described by Menand et al (2002). TOR and RAPTOR genes were found to be expressed constitutively in various tissues of Arabidopsis at low levels, and the expression levels did not change significantly during different physiological conditions (our unpublished data; see also Menand et al, 2002;Robaglia et al, 2004;Deprost et al, 2005), indicating that TOR may be regulated by some posttranscriptional/ translational mechanisms (Robaglia et al, 2004).…”

Section: Raptor1 Interacts With the Heat Repeats Of Tormentioning

confidence: 53%

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Arabidopsis TARGET OF RAPAMYCIN Interacts with RAPTOR, Which Regulates the Activity of S6 Kinase in Response to Osmotic Stress Signals

et al. 2005

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TARGET OF RAPAMYCIN (TOR) kinase controls many cellular functions in eukaryotic cells in response to stress and nutrient availability and was shown to be essential for embryonic development in Arabidopsis thaliana. We demonstrated that Arabidopsis RAPTOR1 (a TOR regulatory protein) interacts with the HEAT repeats of TOR and that RAPTOR1 regulates the activity of S6 kinase (S6K) in response to osmotic stress. RAPTOR1 also interacts in vivo with Arabidopsis S6K1, a putative substrate for TOR. S6K1 fused to green fluorescent protein and immunoprecipitated from tobacco (Nicotiana tabacum) leaves after transient expression was active in phosphorylating the Arabidopsis ribosomal S6 protein. The catalytic domain of S6K1 could be phosphorylated by Arabidopsis 3-phosphoinositide-dependent protein kinase-1 (PDK1), indicating the involvement of PDK1 in the regulation of S6K. The S6K1 activity was sensitive to osmotic stress, while PDK1 activity was not affected. However, S6K1 sensitivity to osmotic stress was relieved by co-overexpression of RAPTOR1. Overall, these observations demonstrated the existence of a functional TOR kinase pathway in plants. However, Arabidopsis seedlings do not respond to normal physiological levels of rapamycin, which appears to be due its inability to bind to the Arabidopsis homolog of FKBP12, a protein that is essential for the binding of rapamycin with TOR. Replacement of the Arabidopsis FKBP12 with the human FKBP12 allowed rapamycin-dependent interaction with TOR. Since homozygous mutation in TOR is lethal, it suggests that this pathway is essential for integrating the stress signals into the growth regulation.

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Section: Raptor1 Interacts With the Heat Repeats Of Tormentioning

confidence: 53%

“…This pathway may link various stress signals to the growth signal pathways optimizing plant growth under different environmental conditions. Preliminary evidence suggests that a posttranscriptional mechanism may play a role in the regulation of the TOR pathway (Robaglia et al, 2004).…”

Section: Target Of Rapamycin (Tor) Is An Evolutionarily Conservedmentioning

confidence: 99%

Arabidopsis TARGET OF RAPAMYCIN Interacts with RAPTOR, Which Regulates the Activity of S6 Kinase in Response to Osmotic Stress Signals

et al. 2005

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“…In Arabidopsis, AtTOR-GUS fusion protein expression occurred in proliferating cells and tissues, such as embryo and primary meristems, but not in differentiated organs such as fully expanded leaf and root tissues (Menand et al 2002). However, AtTOR mRNA was detected at nearly equal levels in all plant tissues (Robaglia et al 2004). These results indicated the post-transcriptional regulation of AtTOR gene expression.…”

Section: Discussionmentioning

confidence: 95%

Evolutionary conservation of TORC1 components, TOR, Raptor, and LST8, between rice and yeast

et al. 2015

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Target of rapamycin (TOR) is a conserved eukaryotic serine/threonine kinase that functions as a central controller of cell growth. TOR protein is structurally defined by the presence several conserved domains such as the HEAT repeat, focal adhesion target (FAT), FKBP12/rapamycin binding (FRB), kinase, and FATC domains starting from the N-terminus. In most eukaryotes, TOR forms two distinct physical and functional complexes, which are termed as TOR complex 1 (TORC1) and TORC2. However, plants contain only TORC1 components, i.e., TOR, Raptor, and LST8. In this study, we analyzed the gene structure and functions of TORC components in rice to understand the properties of the TOR complex in plants. Comparison of the locations of introns in these genes among rice and other eukaryotes showed that they were well conserved among plants except for Chlamydomonas. Moreover, the intron positions in the coding sequence of human Raptor and LST8 were closer to those of plants than of fly or nematode. Complementation tests of rice TOR (OsTOR) components in yeast showed that although OsTOR did not complement yeast tor mutants, chimeric TOR, which consisted of the HEAT repeat and FAT domain from yeast and other regions from rice, rescued the tor mutants, indicating that the HEAT repeat and FAT domains are important for species-specific signaling. OsRaptor perfectly complemented a kog1 (yeast Raptor homolog) mutant, and OsLST8 partially complemented an lst8 mutant. Together, these data suggest the importance of the N-terminal region of the TOR, HEAT, and FAT domains for functional diversification of the TOR complex.

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“…Arabidopsis thaliana) and nematodes (i.e. Caenorhabditis elegans) being notable exceptions Robaglia et al, 2004). As rapamycin is produced by a soil bacterium, it is probable that, like A. thaliana and C. elegans, many eukaryotes that live in soil have developed natural resistance to rapamycin.…”

Section: Discovery Of Tormentioning

confidence: 99%

Cell growth control: little eukaryotes make big contributions

2006

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The story of rapamycin is a pharmaceutical fairytale. Discovered as an antifungal activity in a soil sample collected on Easter Island, this macrocyclic lactone and its derivatives are now billion dollar drugs, used in, and being evaluated for, a number of clinical applications. Taking advantage of its antifungal property, the molecular Target Of Rapamycin, TOR, was first described in the budding yeast Saccharomyces cerevisiae. TORs encode large, Ser/Thr protein kinases that reside in two distinct, structurally and functionally conserved, multi-protein complexes. In yeast, these complexes coordinate many different aspects of cell growth. TOR complex 1, TORC1, promotes protein synthesis and other anabolic processes, while inhibiting macroautophagy and other catabolic and stress-response processes. TORC2 primarily regulates cell polarity, although additional readouts of this complex are beginning to be characterized. TORC1 appears to be activated by nutrient cues and inhibited by stresses and rapamycin; however, detailed mechanisms are not known. In contrast, TORC2 is insensitive to rapamycin and physiological regulators of this complex have yet to be defined. Given the unsurpassed resources available to yeast researchers, this simple eukaryote continues to contribute to our understanding of eukaryotic cell growth in general and TOR function in particular

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Plant growth: the translational connection

Cited by 24 publications

References 23 publications

Arabidopsis TARGET OF RAPAMYCIN Interacts with RAPTOR, Which Regulates the Activity of S6 Kinase in Response to Osmotic Stress Signals

Arabidopsis TARGET OF RAPAMYCIN Interacts with RAPTOR, Which Regulates the Activity of S6 Kinase in Response to Osmotic Stress Signals

Evolutionary conservation of TORC1 components, TOR, Raptor, and LST8, between rice and yeast

Cell growth control: little eukaryotes make big contributions

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