A Cysteine Protease Gene Is Expressed Early in Resistant Potato Interactions with Phytophthora infestans

Abstract

A potato cysteine protease (cyp) cDNA expressed at an early stage of an incompatible interaction with Phytophthora infestans was isolated. Both the nucleotide and deduced amino acid sequences are highly homologous to those of a tomato cysteine protease, CYP1. Striking protein similarity to all known cathepsins in animals, particularly cathepsin K, was also observed. However, unlike cathepsins, a granulin binding domain is located near the carboxyl terminus of the putative CYP protein. In animals, granulins bind to receptors in the plasma membrane and signal cell growth and division. A ribonuclease protection assay demonstrated that the cyp gene is tightly regulated and is induced 15 h post inoculation with P. infestans in potato leaves either with high field resistance or in which a resistance (R) gene is activated. We conclude that a common signaling pathway is activated in each form of resistance.

Characterization of Solanum tuberosum Multicystatin and Its Structural comparison with Other Cystatins

“…However, the identified potato Cys protease has a molecular mass of ;51 kD, which differs from the observed molecular mass of ;45 kD (Figure 9), suggesting the protein is posttranslationally modified or is the product of another gene not identified due to incomplete sequencing of the potato genome. In a previous report (Avrova et al, 1999), the putative Cys protease identified here was found to be tightly regulated and to be induced by Phytophthora infestans in potato leaves. Considering a high level of sequence similarity to cathepsin K and the existence of a granulin binding domain in the C terminus, the putative Cys protease has been proposed to have caspase-like regulatory function through a specific target mechanism of its granulin binding domain (Avrova et al, 1999).…”

“…Analysis of the eluted proteins by SDS-PAGE revealed one predominant protein band of ;45 kD, a PMC-2 band of ;10 kD, and a number of less intense bands ( Figure 9). LC-MS/MS analysis detected three peptides, ID-SYEDVPVNNEK, AVAHQPVSIAIEAGGR, and NVASSSGLCGLA-TEPSYPVK, which were used to identify the predominant protein as a 466-amino acid putative Cys protease from S. tuberosum (Avrova et al, 1999).…”

“…The major protein band in the PMC pull-down assay was identified as a putative Cys protease (Avrova et al, 1999). However, the significance of the other faint bands in Figure 9 cannot be ignored, and their identity is under investigation.…”

Granulosain I, a Cysteine Protease Isolated from Ripe Fruits of Solanum granuloso -leprosum (Solanaceae)

“…The majority of the existing reports come from physiological studies or gene expression from these enzymes under conditions of stress or pathogen attack [28,44].…”

“…Little is known about the physiological functions of these peptidase. In plants, for example, they have been associated with the mobilization of nutrients and defence against pathogens [3,28,47]. Many of these enzymes have important applications in medicine and biotechnology.…”