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Molecular adaptations to fluctuating environments


since 2013 - heute

The maintenance of cellular energy homeostasis in response to fluctuating internal and external conditions is vital for all living organisms. In eukaryotes, an evolutionarily conserved protein kinase, known as SNF1-related protein kinase 1 (SnRK1) in plants, integrates environmental stress signals, nutrient availability and energy depletion into adaptational responses.

Cooperation Partners

Max-Planck-Institute of Molecular Plant Physiology
Friedrich-Alexander-University Erlangen-Nuremberg

These include down-regulation of ATP-consuming processes and induction of energy-generating catabolic reactions through post-translational modification of key metabolic enzymes as well as large-scale transcriptional reprogramming. Although SnRK1 acts as a convergent point for many different environmental and metabolic signals to control growth and development, it is currently unknown how these many different signals could be translated into a cell-type or stimulus specific response. Using a combination of metabolite profiling, flux analysis, and transcriptome profiling we were able to show that the metabolite trehalose-6-phosphate serves as a signal for sucrose availability in potato tubers. High T6P content correlates with high sucrose levels and under these conditions T6P directly inhibits SnRK1 activity allowing for active growth. On the contrary, SnRK1 signaling is activated in transgenic tuber expressing a T6P degrading enzyme. SnRK1 activation leads to reduced tuber growth and massive shifts in carbohydrate metabolism.

Further studies, using Arabidopsis thaliana as a model system, identified domain of unknown function (DUF)-581 containing proteins as possible adaptors mediating stimulus specific SnRK1 responses. DUF581 proteins bind to SnRK1 via their conserved domain while they are able to interact with potential SnRK1 substrate proteins through a variable region. The analysis of available microarray data implies that expression of the 19 members of the DUF581 encoding gene family in Arabidopsis is differentially regulated by hormones and environmental cues, indicating specialized functions of individual family members. We hypothesize that DUF581 proteins could act as mediators conferring tissue- and stimulus-type specific differences in SnRK1 regulation. To further elucidate the role of DUF581 containing proteins in SnRK1 signaling we use a combination of genetic, biochemical and cell biological approaches. This includes the analysis of Arabidopsis knock-out or knock-down lines for individual DUF581 family members or combinations thereof for changes in adaptive growth responses under certain stresses such as prolonged darkness, hypoxia, drought or mineral nutrient deficiency.