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Proteolytic processing in plant stress signal transduction and responses to abiotic stress and pathogen attack

Periodic Reporting for period 3 - ProPlantStress (Proteolytic processing in plant stress signal transduction and responses to abiotic stress and pathogen attack)

Reporting period: 2018-06-01 to 2019-11-30

As sessile organisms, plants need robust mechanisms to perceive multiple environmental stress conditions and must be able to mount appropriate responses. An improved understanding of the molecular mechanisms underlying these stress responses promises to reveal new opportunities for crop breeding, crop protection and pest management, which will be needed to satisfy future demands for agricultural productivity.
ProPlantStress focuses on a biochemical mechanism termed proteolytic processing that has been implicated in several plant stress signaling and stress response pathways but is poorly understood on a system-wide level. Proteolysis is the hydrolysis of a peptide bond, resulting in cleavage/truncation of proteins. This reaction is catalyzed by a family of enzymes called proteases. We aim to better understand which proteins are cut by which proteases, how this changes the target protein function and what this means for the plant´s ability to cope with stress.
To identify proteolytic processes in living systems, one must be able to determine the termini, the start and end points of a protein. We have established “degradomics” methods to do so for hundreds to thousands of protein N termini (the start points) in complex plant samples using mass spectrometry. These methods have originally been developed to address medical questions, but have now been adapted to and optimized for plants samples. Mass spectrometry not only allows us to identify protein termini, but also to compare their relative abundance. We are using these techniques to determine which proteins are cut in plants exposed to stress compared to control conditions. Similarly, we are using these methods to identify the substrate of selected proteases of interest by comparison of plants with modulated proteolytic activity.
We can now determine much more protein termini in plants than before, providing us with more detailed information which includes several low-abundance proteins that may have regulatory functions. We expect that ProPlantStress will lead to a more systematic understanding of the role of proteolytic protein modifications and the role of selected proteases in plant responses to abiotic stress and defense against bacterial pathogens. We hope that this will reveal opportunities for improved plant protection, as many proteases involved in human disease have been successfully targeted by selective drugs.