Phytaspase, a relocalisable cell death promoting plant protease with caspase specificity

作者：Chichkova Nina V; Shaw Jane; Galiullina Raisa A; Drury Georgina E; Tuzhikov Alexander I; Kim Sang Hyon; Kalkum Markus; Hong Teresa B; Gorshkova Elena N; Torrance Lesley; Vartapetian Andrey B^*; Taliansky Michael

来源：The EMBO Journal, 2010, 29(6): 1149-1161.

DOI：10.1038/emboj.2010.1

• abiotic stress
• caspases
• programmed cell death
• subtilisin-like proteases
• tobacco mosaic virus

Caspases are cysteine-dependent proteases and are important components of animal apoptosis. They introduce specific breaks after aspartate residues in a number of cellular proteins mediating programmed cell death (PCD). Plants encode only distant homologues of caspases, the metacaspases that are involved in PCD, but do not possess caspase-specific proteolytic activity. Nevertheless, plants do display caspase-like activities indicating that enzymes structurally distinct from classical caspases may operate as caspase-like proteases. Here, we report the identification and characterisation of a novel PCD-related subtilisin-like protease from tobacco and rice named phytaspase (plant aspartate-specific protease) that possesses caspase specificity distinct from that of other known caspase-like proteases. We provide evidence that phytaspase is synthesised as a proenzyme, which is autocatalytically processed to generate the mature enzyme. Overexpression and silencing of the phytaspase gene showed that phytaspase is essential for PCD-related responses to tobacco mosaic virus and abiotic stresses. Phytaspase is constitutively secreted into the apoplast before PCD, but unexpectedly is re-imported into the cell during PCD providing insights into how phytaspase operates. The EMBO Journal (2010) 29, 1149-1161. doi: 10.1038/emboj.2010.1; Published online 28 January 2010

• 出版日期2010-3-17