Martinez Manuel, Diaz-Mendoza Mercedes, Carrillo Laura, Diaz Isabel
Laboratorio de Bioquímica y Biología Molecular, Departamento de Biotecnología, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, ETS Ingenieros Agrónomos, Madrid, Spain.
FEBS Lett. 2007 Jun 26;581(16):2914-8. doi: 10.1016/j.febslet.2007.05.042. Epub 2007 May 25.
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.
植物天冬酰胺酶是一种半胱氨酸蛋白酶，推测参与内源性蛋白质的加工过程。植物胱抑素（PhyCys）已被描述为木瓜蛋白酶样半胱氨酸蛋白酶的植物抑制剂。一些PhyCys含有一个羧基末端延伸部分，其氨基酸基序（SNSL）与人类胱抑素抑制类天冬酰胺酶蛋白所涉及的基序相似。这些羧基末端延伸的PhyCys作为类天冬酰胺酶半胱氨酸蛋白酶抑制剂的作用，在此通过体外抑制人天冬酰胺酶和大麦提取物中的类天冬酰胺酶活性得以证明。此外，定点诱变已证明SNSL基序中的天冬酰胺在这种抑制中至关重要。我们首次证明了植物中存在天冬酰胺酶抑制剂。
