The Arabidopsis METACASPASE9 Degradome |
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| Authors: | Liana Tsiatsiani Evy Timmerman Pieter-Jan De Bock Dominique Vercammen Simon Stael Brigitte van de Cotte An Staes Marc Goethals Tine Beunens Petra Van Damme Kris Gevaert Frank Van Breusegem |
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| Affiliation: | aDepartment of Plant Systems Biology, VIB, 9052 Ghent, Belgium;bDepartment of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium;cDepartment of Medical Protein Research, VIB, 9000 Ghent, Belgium;dDepartment of Biochemistry, Ghent University, 9000 Ghent, Belgium |
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| Abstract: | Metacaspases are distant relatives of the metazoan caspases, found in plants, fungi, and protists. However, in contrast with caspases, information about the physiological substrates of metacaspases is still scarce. By means of N-terminal combined fractional diagonal chromatography, the physiological substrates of METACASPASE9 (MC9; AT5G04200) were identified in young seedlings of Arabidopsis thaliana on the proteome-wide level, providing additional insight into MC9 cleavage specificity and revealing a previously unknown preference for acidic residues at the substrate prime site position P1′. The functionalities of the identified MC9 substrates hinted at metacaspase functions other than those related to cell death. These results allowed us to resolve the substrate specificity of MC9 in more detail and indicated that the activity of phosphoenolpyruvate carboxykinase 1 (AT4G37870), a key enzyme in gluconeogenesis, is enhanced upon MC9-dependent proteolysis. |
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