New insights into lectin from Abelmoschus esculentus seeds as a Kunitz-type inhibitor and its toxic effects on Ceratitis capitata and root-knot nematodes Meloidogyne spp

• Published in: Process biochemistry (1991) 2017-12, Vol.63, p.96-104
• Main Authors: de Lacerda, José Thalles Jocelino Gomes, e Lacerda, Rodrigo Rodrigues, Assunção, Nilson Antonio, Tashima, Alexandre Keiji, Juliano, Maria Aparecida, dos Santos, Gilberto Alves, dos Santos de Souza, Mileny, de Luna Batista, Jacinto, Rossi, Carlos Eduardo, de Almeida Gadelha, Carlos Alberto, Santi-Gadelha, Tatiane
• Format: Article
• Language: English
• Subjects: Abelmoschus esculentus; Carbohydrates; Cathepsin D; Ceratitis capitata; Chymotrypsin; Cysteine proteinase; Dimethoate; Endopeptidase; Hatching; Homology; Immune system; Insecticide resistance; Larvae; Lectin; Lectins; Ligands; Malathion; Mass spectrometry; Meloidogyne; Meloidogyne incognita; Meloidogyne javanica; Nematodes; Organophosphates; Papain; Pathogens; Pest control; Plants (botany); Protease; Protease inhibitor; Protease inhibitors; Seeds; Serine; Studies; Toxicity; Trypsin
• ISSN: 1359-5113; 1873-3298
• DOI: 10.1016/j.procbio.2017.09.003

[Display omitted] •This is the first study on the characterization of the Abelmoschus esculentus lectin (AEL) based on proteomic analysis.•AEL is a Kunitz-type inhibitor with lectin-like domain.•AEL inhibits the activities of serine and cysteine proteases but not aspartyl protease.•AEL showed toxic effects on Ceratitis capitata and was more effective in the pupal stage.•AEL affects the hatching second-stage juvenile ratio of Meloidogyne incognita and Meloidogyne javanica. Plants produce lectins to confer resistance to pathogens through specific carbohydrate binding. The classification of lectins based only ligands can sometimes obscure other functions intrinsic to its structure. In this work, we characterized Abelmoschus esculentus lectin (AEL) on the basis of structural insights and reported its toxic effects on the Mediterranean fruit fly Ceratitis capitata and root-knot nematodes Meloidogyne incognita and Meloidogyne javanica. LC–MS/MS analysis followed by SPIDER searches and de novo sequencing indicated AEL as a Kunitz-type protease inhibitor homologous to the 21-kDa seed protein of Theobroma cacao, an endopeptidase inhibitor. AEL inhibited the activities of trypsin (Ki=3.3nM), chymotrypsin (Ki=8.3nM), and papain (Ki=0.5μM) but not cathepsin D. Insecticidal activity was evaluated in the first, second, and third instar larvae and pupae, in which AEL (2000μg/mL) was more effective on the pupal stage, showing more toxicity than the organophosphates malathion and dimethoate. AEL (500μg/mL) inhibited the hatching of second-stage juveniles in both nematode species, with greater inhibition occurring in M. incognita. The Kunitz-type serine/cysteine protease inhibitor activities of AEL and its pest control effects may provide a novel understanding of its mechanisms in the plant immune system and their biotechnological applications.