Oxidative stress & Cell death projects Metacaspases
Celldeath research
| Metacaspases |
| Oxidative stress & Cell death | |||
 Metacaspases are a recently discovered family of distant caspase homologs in plants, fungi and protozoa. Caspases are cysteine-dependent aspartate-specific proteases that play a prominent role as the “death executioners” in apoptotic cell death in mammalian systems. Caspases cut a wide range of apoptotic substrates finally resulting in cell death. In plants, programmed cell death shares morphological features with mammals, although the molecular mechanisms underlying this process are mostly unknown.The Arabidopsis thaliana genome contains 9 metacaspase genes. The presence or absence of an N-terminal “prodomain”, separates metacaspases into two categories: Type I (MC1 to MC3, with a prodomain) and Type II (MC4 to MC9, without this domain), respectively. We demonstrated that recombinant Type II metacaspases -in contrast to mammalian caspases- are arginine/lysine-specific cysteine dependent proteases. A screening of a combinatorial tetrapeptide library of approximately 130,321 substrates with AtMC9, indicated the tetrapeptide Val-Arg-Pro-Arg as the optimized substrate. Recently, we identified a serine protease inhibitor (AtSerpin1) as a potent inhibitor of AtMC9 activity in vitro through cleavage of its reactive center loop and covalent binding to AtMC9. Currently a detailed phenotypic analysis of plants with perturbed metacaspase levels is ongoing.
Further reading Belenghi, B., Del Carmen Romero-Puertas, M., Vercammen, D., Brackenier, A., Inze, D., Delledonne, M., and Van Breusegem, F. (2007). Metacaspase activity of Arabidopsis thaliana is regulated by S-nitrosylation of a critical cysteine residue. J Biol Chem. 282, 1352-1358. Vercammen, D., Belenghi, B., van de Cotte, B., Beunens, T., Gavigan, J.A., De Rycke, R., Brackenier, A., Inze, D., Harris, J.L., and Van Breusegem, F. (2006). Serpin1 of Arabidopsis thaliana is a Suicide Inhibitor for Metacaspase 9. J Mol Biol 364, 625-636. Eeckhout, D., De Clercq, A., Van De Slijke, E., Van Leene, J., Stals, H., Casteels, P., Persiau, G., Vercammen, D., Van Breusegem, F., Zabeau, M., Inze, D., Jespers, L., Depicker, A., and De Jaeger, G. (2004). A technology platform for the fast production of monoclonal recombinant antibodies against plant proteins and peptides. J Immunol Methods 294, 181-187. Vercammen, D., van de Cotte, B., De Jaeger, G., Eeckhout, D., Casteels, P., Vandepoele, K., Vandenberghe, I., Van Beeumen, J., Inze, D., and Van Breusegem, F. (2004). Type II metacaspases Atmc4 and Atmc9 of Arabidopsis thaliana cleave substrates after arginine and lysine. J Biol Chem. 279, 45329-45336.
|