Silva Nadia C M, De Sá Leonardo F R, Oliveira Eduardo A G, Costa Monique N, Ferreira Andre T S, Perales Jonas, Fernandes Kátia V S, Xavier-Filho Jose, Oliveira Antonia E A
Laboratório de Quı́mica e Função de Proteı́nas e Peptı́deos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro-UENF , 28013602 Campos dos Goytacazes, RJ, Brazil.
Laboratório de Toxinologia, Fundação Oswaldo Cruz , Rio de Janeiro, FIOCRUZ-RJ, Brazil.
J Agric Food Chem. 2016 May 11;64(18):3514-22. doi: 10.1021/acs.jafc.6b00549. Epub 2016 Apr 26.
The seed coat is an external tissue that participates in defense against insects. In some nonhost seeds, including Albizia lebbeck, the insect Callosobruchus maculatus dies during seed coat penetration. We investigated the toxicity of A. lebbeck seed coat proteins to C. maculatus. A chitin-binding protein fraction was isolated from seed coat, and mass spectrometry showed similarity to a C1 cysteine protease. By ELM program an N-glycosylation interaction motif was identified in this protein, and by molecular docking the potential to interact with N-acetylglucosamine (NAG) was shown. The chitin-binding protein fraction was toxic to C. maculatus and was present in larval midgut and feces but not able to hydrolyze larval gut proteins. It did not interfere, though, with the intestinal cell permeability. These results indicate that the toxicity mechanism of this seed coat fraction may be related to its binding to chitin, present in the larvae gut, disturbing nutrient absorption.
种皮是一种参与抵御昆虫的外部组织。在一些非寄主种子中，包括阔荚合欢，害虫绿豆象在穿透种皮的过程中死亡。我们研究了阔荚合欢种皮蛋白对绿豆象的毒性。从种皮中分离出一种几丁质结合蛋白组分，质谱分析表明其与一种C1半胱氨酸蛋白酶相似。通过ELM程序在该蛋白中鉴定出一个N-糖基化相互作用基序，通过分子对接显示其具有与N-乙酰葡糖胺（NAG）相互作用的潜力。该几丁质结合蛋白组分对绿豆象有毒，存在于幼虫中肠和粪便中，但不能水解幼虫肠道蛋白。不过，它并未干扰肠道细胞的通透性。这些结果表明，该种皮组分的毒性机制可能与其与幼虫肠道中存在的几丁质结合有关，从而干扰营养吸收。
