Purification and characterization of an aspartic protease from potato leaves

Abstract

A protease was isolated from potato (Solanum tuberosum L. cv. Pampeana) leaves 48 h after detaching, when aspartic protease (AP) activity is markedly increased. Purification was performed by ammonium sulfate precipitation, ion exchange chromatography and affinity chromatography. A size of 40 kDa was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; it is monomeric and its properties are consistent with those of aspartic proteinases (EC 3.4.23): it has a pH optimum of 3 and it is inhibited by pepstatin. Like other plant APs, leaf AP appears to be glycosylated with a complex-type N-glycan. The enzyme has properties different from those of a tuber AP previously described, indicating that they may have different physiological roles.

Antimicrobial activity of potato aspartic proteases (StAPs) involves membrane permeabilization

“…We have identified three potato (Solanum tuberosum) aspartic proteases, one from tubers (StAP1) (Guevara et al, 1999) and two from leaves (StAP2 and StAP3) (Guevara et al, 2001). Two of these isoforms, StAP1 and StAP3, have been purified and characterized.…”

“…Two of these isoforms, StAP1 and StAP3, have been purified and characterized. Both proteins are induced by both abiotic and biotic stress (Guevara et al, 2001(Guevara et al, , 2002, have an extracellular localization and produce a direct inhibitory effect in vitro on the germination of cysts of Phytophthora infestans and conidia of Fusarium solani (Guevara et al, 2002(Guevara et al, , 2004.…”

The inter-generic fungicidal activity of Xanthophyllomyces dendrorhous

“…In plants, the production of proteases is believed to be a general defense mechanism against pathogenic fungi. Secretion of aspartic proteases with antimicrobial activity against Phytophthora infestans and the conidia of Fusarium solani has been described in potato tubers (Solanum tuberosum) after infection and damage to the intercellular fluids (Guevara et al, 2001(Guevara et al, , 2002(Guevara et al, , 2005Mendieta et al, 2006).…”

Native and Biotechnologically Engineered Plant Proteases with Industrial Applications

“…Plant APs are widely distributed among gymnosperms. AP activity has been detected in the seeds of pine species (Salmia 1981), whereas in angiosperms, APs have been detected in monocotyledonous plants such as barley, rice, wheat, sorghum, and maize (Asakura et al 1995;Asakura et al 1997;Sarkkinen et al 1992;Belozersky et al 1989;Radlowski et al 1996;Garg and Virupaks 1970), and in dicotyledonous plants like sunflower, cacao, Arabidopsis, Brassica, spinach, potato, tobacco, tomato, Cynara cardunculus, Centaurea calcitrapa, and carnivorous plants such as Nepenthes (Park et al 2001;Domingos et al 2000;Heimgartner et al 1990;D'Hondt et al 1997;Voigt et al 1995;Guevara et al 2001;Rodrigo et al 1989;Tokes et al 1974;Kuwabara and Suzuki 1995;Guilloteau et al 2005).…”