Investigating the role of TOR kinase in the Arabidopsis circadian clock
Lead Research Organisation:
University of Cambridge
Department Name: Plant Sciences
Abstract
PhD project strategic theme: Bioscience for sustainable agriculture and food
Target of rapamycin (TOR) is a protein kinase that has been shown to be widely involved in eukaryotic signalling networks. Interestingly, TOR has been found to have a role in glucose energy signalling in Arabidopsis meristem activation. A significant overlap of glucose-TOR-regulated genes and nicotinamide-regulated genes from a circadian clock study was observed. From this, it was discovered that silencing TOR expression increases the period of the Arabidopsis circadian clock. In addition to this, circadian responses to sugars were altered in the TOR null. The circadian period normally shortens in response to glucose treatment, however in the absence of TOR expression plants were period insensitive to exogenous glucose.
The proposed project aims to further investigate this role of TOR signalling in the Arabidopsis circadian clock. One specific aim is to determine how exactly TOR kinase inputs into the circadian clock. One hypothesis is that the effect of TOR on the circadian period is through PRR7, a core clock protein known to be involved in circadian entrainment to sugars. Experiments to test this hypothesis would include protein work, such as yeast two-hybrid, to identify any potential interactions between TOR kinase and PRR7. Additional work would look at regulatory-associated protein of mTOR (RAPTOR) which is a TOR scaffold protein, knockout mutants of RAPTOR have been found to be long period and affected in both growth and flowering time. One specific question is whether TOR or RAPTOR are involved in entrainment of the circadian clock to sugars and if so, what are the molecular pathways by which they regulate the circadian oscillator.
Target of rapamycin (TOR) is a protein kinase that has been shown to be widely involved in eukaryotic signalling networks. Interestingly, TOR has been found to have a role in glucose energy signalling in Arabidopsis meristem activation. A significant overlap of glucose-TOR-regulated genes and nicotinamide-regulated genes from a circadian clock study was observed. From this, it was discovered that silencing TOR expression increases the period of the Arabidopsis circadian clock. In addition to this, circadian responses to sugars were altered in the TOR null. The circadian period normally shortens in response to glucose treatment, however in the absence of TOR expression plants were period insensitive to exogenous glucose.
The proposed project aims to further investigate this role of TOR signalling in the Arabidopsis circadian clock. One specific aim is to determine how exactly TOR kinase inputs into the circadian clock. One hypothesis is that the effect of TOR on the circadian period is through PRR7, a core clock protein known to be involved in circadian entrainment to sugars. Experiments to test this hypothesis would include protein work, such as yeast two-hybrid, to identify any potential interactions between TOR kinase and PRR7. Additional work would look at regulatory-associated protein of mTOR (RAPTOR) which is a TOR scaffold protein, knockout mutants of RAPTOR have been found to be long period and affected in both growth and flowering time. One specific question is whether TOR or RAPTOR are involved in entrainment of the circadian clock to sugars and if so, what are the molecular pathways by which they regulate the circadian oscillator.
