CASPASE- 3 LIKE ACTIVITY IN Solanum tuberosum-P. infestans INTERACTION

FERNÁNDEZ, MB; DALEO, GR; GUEVARA, MG

Puerto Madryn, Chubut, Argentina

Congreso; XLVI Reunión Anual SAIB; 2010

Caspases are key components in animal programmed cell death. In the last decade, caspase like activities were described during different plant developmental and defense responses. Here wepresent a new plant-pathogen system where caspase-3 like activity was detected. Protein extracts from Solanum tuberosum leaves infected with Phytophthora infestans for 0, 1, 6, 12, 24 and 48 h were prepared. Higher relative DEVDase activity was detected at pH 5,2 and 37ºC after 24 h of P. infestans infection. This activity was significantly inhibited (85%) when extracts were preincubated for 1 h with specific DEVDase inhibitor (Ac-DEVDCHO 50 μM). General protease and caspase inhibitors had noeffect (2,5 mM PMSF, 100 μM E-64, 10 μM E-64, 0,5 mM Pepstatin A and 50 μM Z-VAD-FMK). An in silico prediction analysis of potential caspase-like cleavage site (DEVD) restricted to S. tuberosum revealed 7 predicted proteins in GenPep, 16 in TrEMBL and 1 in Swiss Prot databases with at least one DEVD motif. Most of these proteins correspond to apoptosis related proteins and transcription factors. Finally, this DEVDase activity appears to be related to animal caspases, since it is insensitive to broad-range general protease inhibitors. However, in contrast to animal caspase 3 which is active at pH 7, DEVDase ativity was active at acidic pH, possibly suggesting a vacuolar or mitochondrial intermembrane localization.