Characterization of inhibitory mechanism and antifungal activity between group-1 and group-2 phytocystatins from taro (Colocasia esculenta)
Resource
FEBS Journal 275 (20): 4980-4989
Journal
FEBS Journal
Journal Volume
275
Journal Issue
20
Pages
4980-4989
Date Issued
2008
Date
2008
Author(s)
Abstract
Tarocystatin from Colocasia esculenta, a group-2 phytocystatin, is a defense protein against phytopathogenic nematodes and fungi. It is composed of a highly conserved N-terminal region, which is homological to group-1 cystatin, and a repetitive peptide at the C-terminus. The purified recombinant proteins of tarocystatin, such as full-length (FL), N-terminus (Nt) and C-terminus (Ct) peptides, were produced and their inhibitory activities against papain as well as their antifungal effects were investigated. Kinetic analysis revealed that FL peptide exhibited mixed type inhibition (Kia = 0.098 μm and Kib = 0.252 μm) and Nt peptide showed competitive inhibition (Ki = 0.057 μm), whereas Ct peptide possessed weak papain activation properties. A shift in the inhibitory pattern from competitive inhibition of Nt peptide alone to mixed type inhibition of FL peptide implied that the Ct peptide has an regulatory effect on the function of FL peptide. Based on the inhibitory kinetics of FL (group-2) and Nt (group-1) peptides on papain activity, an inhibitory mechanism of group-2 phytocystatins and a regulatory mechanism of extended Ct peptide have each been proposed. By contrast, the antifungal activity of Nt peptide appeared to be greater than that of FL peptide, and the Ct peptide showed no effect on antifungal activity, indicating that the antifungal effect is not related to proteinase inhibitory activity. The results are valid for most phytocystatins with respect to the inhibitory mechanism against cysteine proteinase. © 2008 The Authors.
Subjects
Allosteric activation; Anti-fungal activity; Cysteine proteinase inhibitor; Inhibitory kinetics; Tarocystatin (CeCPI)
Other Subjects
cysteine proteinase inhibitor; papain; phytocystatin; unclassified drug; amino terminal sequence; antifungal activity; article; carboxy terminal sequence; Colocasia; Colocasia esculenta; competitive inhibition; enzyme activation; enzyme inhibition; nonhuman; priority journal; regulatory mechanism; Antifungal Agents; Colocasia; Cystatins; Cysteine Proteinase Inhibitors; Kinetics; Papain; Peptide Fragments; Phytotherapy; Recombinant Proteins; Colocasia esculenta; Fungi; Nematoda
Type
journal article
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