WG 1: Functional characterisation of protein kinases involved in abiotic stress signalling.
WG 1: Functional characterisation of protein kinases involved in abiotic stress signalling.
WG1 will concentrate on understanding the regulatory roles of two major classes of protein kinases, the activities of which are differentially controlled by specific abiotic stress stimuli and the plant hormone abscisic acid (ABA). The SnRK1 class of AMP-activated protein kinases is activated by all stress stimuli that alter the energy balance of cells by increasing the AMP/ATP ratio. Catalytic subunits of SnRK1 kinases are closely related to those of SnRK2 family represented by 10 genes in Arabidopsis: SnRK2s are selectively activated by ABA, osmotic and salt stress both at the levels of transcription and stimulus-induced phosphorylation. Data from the collaboration partners show that SnRK2 kinases cross-talk with early phospholipid signalling; interact with negative regulators of ABA signalling, down-regulate signalling by reactive oxygen species (ROS) and control key transcription factors in several stress signalling cascades. SnRK1 and SnRK2 kinases can recognize common substrates, and likely act in similar pathways. SnRK1s are implicated in the control of stability and proteasomal degradation of signalling and transcription factors. Transcript profiling data indicate that SnRK1 kinases regulate the expression of over 1,000 stress responsive genes, whereas the range of genomic targets of SnRK2s is yet unknown. Research in WG1 will focus on:
WG1.1 Study the regulatory roles of SnRK1/2 kinases in osmotic, salt, cold and metabolic signalling pathways using mutations, conditional overexpression of dominantly activated kinase forms, and inhibitions of specific kinase activities by inhibitory RNAi contructs.
WG1.2 Identification of transcriptional regulatory targets of SnRK1/2 kinases using transcript profiling and genetic tools developed in WG1.1
WG1.3 Development of novel genetic technologies for identification of transcription factors and other signalling molecules involved in the control of expression of SnRK1/2 regulated genes.
WG1.4 Identification of SnRK1/2 kinase substrates (i.e., signalling and transcription factors) using phosphoproteomics approaches.
WG1.5 Specific studies of SnRK1/2 regulatory interactions:
- with phospholipase D signalling, aldehyde dehydrogenases (ALDHs) and their links with ROS signalling
- with newly identified elements of parallel abiotic stress signalling pathways
- with already characterized elements of cold and salt stress signalling pathway.
- plant defence responses to bacterial and fungal pathogens,
- genes encoding rate limiting enzymes in proline, glutamate, and glutamate-derived amino acid biosynthesis,
- genes controlling the biosynthesis of other important osmoprotective compounds,
- chaperonins and polyamines in combination with metabolic profiling approaches,
- genes regulating the concentration of methyl donor S-adenosyl-methionine and gene silencing by chromatin modifications.
WG1.7 Development of systems biology approaches for integration of known and newly uncovered functions in various stress signalling pathways.