The interaction of the bioinsecticide PA1b (Pea Albumin 1 subunit b) with the insect V-ATPase triggers apoptosis

• Published in: Scientific reports 2017-07, Vol.7 (1), p.4902-10, Article 4902
• Main Authors: Eyraud, Vanessa, Balmand, Séverine, Karaki, Lamis, Rahioui, Isabelle, Sivignon, Catherine, Delmas, Agnès F., Royer, Corinne, Rahbé, Yvan, Da Silva, Pedro, Gressent, Frédéric
• Format: Article
• Language: English
• Subjects: 631/1647/328; 631/45/611; 82/1; 96/2; 96/63; 96/95; Adenosine triphosphatase; Albumin; Animals; Apoptosis; Caspase; Caspase 3 - genetics; Caspase 3 - metabolism; Caspase-3; Ecology, environment; Enzymatic activity; Gastrointestinal Tract - drug effects; Gastrointestinal Tract - metabolism; Gene Expression Regulation; H+-transporting ATPase; Humanities and Social Sciences; Insect Proteins - antagonists & inhibitors; Insect Proteins - genetics; Insect Proteins - metabolism; Insecticides; Insecticides - isolation & purification; Insecticides - metabolism; Insecticides - toxicity; Insects; Intoxication; Labeling; Life Sciences; Midgut; multidisciplinary; Peptides - isolation & purification; Peptides - metabolism; Peptides - toxicity; Pests; Phytopathology and phytopharmacy; Pisum sativum - chemistry; Pisum sativum - genetics; Pisum sativum - parasitology; Plant Proteins - isolation & purification; Plant Proteins - metabolism; Plant Proteins - toxicity; Protein Binding; Protein Subunits - antagonists & inhibitors; Protein Subunits - genetics; Protein Subunits - metabolism; Science; Science (multidisciplinary); Seeds; Seeds - chemistry; Seeds - genetics; Seeds - parasitology; Sitophilus oryzae; Symbiosis; Toxins; Toxins, Biological - isolation & purification; Toxins, Biological - metabolism; Toxins, Biological - toxicity; Tribolium - drug effects; Tribolium - metabolism; Tribolium castaneum; Vacuolar Proton-Translocating ATPases - antagonists & inhibitors; Vacuolar Proton-Translocating ATPases - genetics; Vacuolar Proton-Translocating ATPases - metabolism; Vegetal Biology; Weevils - drug effects; Weevils - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-05315-y

PA1b (Pea Albumin 1, subunit b) peptide is an entomotoxin, extracted from Legume seeds, with a lethal activity towards several insect pests, such as mosquitoes, some aphids and cereal weevils. This toxin acts by binding to the subunits c and e of the plasma membrane H + -ATPase (V-ATPase) in the insect midgut. In this study, two cereal weevils, the sensitive Sitophilus oryzae strain WAA42, the resistance Sitophilus oryzae strain ISOR3 and the insensitive red flour beetle Tribolium castaneum , were used in biochemical and histological experiments to demonstrate that a PA1b/V-ATPase interaction triggers the apoptosis mechanism, resulting in insect death. Upon intoxication with PA1b, apoptotic bodies are formed in the cells of the insect midgut. In addition, caspase-3 enzyme activity occurs in the midgut of sensitive weevils after intoxication with active PA1b, but not in the midgut of resistant weevils. These biochemical data were confirmed by immuno-histochemical detection of the caspase-3 active form in the midgut of sensitive weevils. Immuno-labelling experiments also revealed that the caspase-3 active form and V-ATPase are close-localized in the insect midgut. The results concerning this unique peptidic V-ATPase inhibitor pave the way for the utilization of PA1b as a promising, more selective and eco-friendly insecticide.