Overney S, Yelle S, Cloutier C
Faculté des Sciences de l'Agriculture et de l'Alimentation, Centre de Recherche en Horticulture, Université Laval, Québec, Canada.
Comp Biochem Physiol B Biochem Mol Biol. 1998 May;120(1):191-5. doi: 10.1016/s0305-0491(98)10008-1.
Oryzacystatins (OCs) are protease inhibitors (PIs) that inhibit Colorado potato beetle (CPB) digestive proteases, and transgenic potato plants containing these PIs are currently under test. However, OCs could interfere with the digestive system of beneficial insects. Protease activity and susceptibility to class-specific protease inhibitors were studied in protein extracts of Perillus bioculatus, a stinkbug predator that has shown potential for biological control of the CPB. At physiological pH, the analysis of protease activity showed that up to 90% of P. bioculatus protease activity is of the cysteine type. All active life stages of the predator were tested, and electrophoretic characterization detected no major qualitative variation in protease pattern between stages. Protease activity in extracts of P. bioculatus nymphs was significantly reduced, up to 70%, by the two recombinant cystatins from rice (OCI and OCII), and by stefin A, a PI encoded by a human gene. These results clearly indicate that cysteine PIs are active not only against the CPB digestive protease complex, but also against proteases of one of its most important natural predators.
水稻半胱氨酸蛋白酶抑制剂（OCs）是一类蛋白酶抑制剂（PIs），可抑制科罗拉多马铃薯甲虫（CPB）的消化蛋白酶，目前含有这些蛋白酶抑制剂的转基因马铃薯植株正在进行试验。然而，OCs可能会干扰有益昆虫的消化系统。本研究对二点委夜蛾（一种对CPB具有生物防治潜力的蝽类捕食者）的蛋白质提取物中的蛋白酶活性以及对特定类别的蛋白酶抑制剂的敏感性进行了研究。在生理pH值下，蛋白酶活性分析表明，二点委夜蛾高达90%的蛋白酶活性属于半胱氨酸类型。对该捕食者的所有活跃生命阶段都进行了测试，电泳分析未检测到不同阶段之间蛋白酶模式存在重大定性差异。来自水稻的两种重组半胱氨酸蛋白酶抑制剂（OCI和OCII）以及人类基因编码的蛋白酶抑制剂stefin A，可使二点委夜蛾若虫提取物中的蛋白酶活性显著降低，降幅高达70%。这些结果清楚地表明，半胱氨酸蛋白酶抑制剂不仅对CPB消化蛋白酶复合体有活性，而且对其最重要的自然捕食者之一的蛋白酶也有活性。
