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Carboxy terminal extended phytocystatins are bifunctional inhibitors of papain and legumain cysteine proteinases
Author(s) -
Martinez Manuel,
Diaz-Mendoza Mercedes,
Carrillo Laura,
Diaz Isabel
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.05.042
Subject(s) - cysteine , biochemistry , papain , cysteine proteinase inhibitors , chemistry , asparagine , amino acid , bifunctional , in vitro , enzyme , biology , programmed cell death , caspase , catalysis , apoptosis
Plant legumains are cysteine proteinases putatively involved in processing endogenous proteins. Phytocystatins (PhyCys) have been described as plant inhibitors of papain‐like cysteine proteinases. Some PhyCys contain a carboxy terminal extension with an amino acid motif (SNSL) similar to that involved in the inhibition of legumain‐like proteins by human cystatins. The role of these carboxy terminal extended PhyCys as inhibitors of legumain‐like cysteine proteinases is here shown by in vitro inhibition of human legumain and legumain‐like activities from barley extracts. Moreover, site‐directed mutagenesis has demonstrated that the asparagine of the SNSL motif is essential in this inhibition. We prove for first time the existence of legumain inhibitors in plants.