title: New mode of action for a knottin protein bioinsecticide: pea albumin 1 subunit b (PA1b) is the first peptidic inhibitor of V-ATPase.
abstract: PA1b (for pea albumin 1 subunit b) is a plant bioinsecticide lethal to several pests that are important in agriculture or human health. PA1b belongs to the inhibitory cystine knot family or knottin family. Originating from a plant (the garden pea) commonly eaten by humans without any known toxic or allergic effects, PA1b is a candidate for transgenic applications and is one of the most promising biopesticides for pest control. Using whole-cell patch-clamp techniques on Sf9 PA1b-sensitive lepidopteran insect cells, we discovered that PA1b reversibly blocked ramp membrane currents in a dose-dependent manner (EC(50) = 0.52 μM). PA1b had the same effect as bafilomycin, a specific inhibitor of the vacuolar proton pump (V-type H(+)-ATPase), and the PA1b-sensitive current depended on the internal proton concentration. Biochemical assays on purified V-ATPase from the lepidopteran model Manduca sexta showed that PA1b inhibited the V(1)V(0)-type H(+)-ATPase holoenzyme activity (IC(50) ∼ 70 nM) by interacting with the membrane-bound V(0) part of the V-ATPase. V-ATPase is a complex protein that has been studied increasingly because of its numerous physiological roles. In the midgut of insects, V-ATPase activity is essential for energizing nutrient absorption, and the results reported in this work explain the entomotoxic properties of PA1b. Targeting V-ATPase is a promising means of combating insect pests, and PA1b represents the first peptidic V-ATPase inhibitor. The search for V-ATPase inhibitors is currently of great importance because it has been demonstrated that V-ATPase plays a role in so many physiological processes.
authors: UMR CNRS 5534, Centre de Génétique et de Physiologie Moléculaires et Cellulaires, Université de Lyon, F-69622 Villeurbanne, France.
authors: Christophe
authors: C
authors: Chouabe
authors: Vanessa
authors: V
authors: Eyraud
authors: Pedro
authors: P
authors: Da Silva
authors: Isabelle
authors: I
authors: Rahioui
authors: Corinne
authors: C
authors: Royer
authors: Christophe
authors: C
authors: Soulage
authors: Robert
authors: R
authors: Bonvallet
authors: Markus
authors: M
authors: Huss
authors: Frédéric
authors: F
authors: Gressent
mesh_terms: D000818:Animals; D002460:Cell Line; D057771:Cystine-Knot Miniproteins / Q000494:pharmacology*; D006801:Humans; D019476:Insect Proteins / Q000037:antagonists & inhibitors*; D007306:Insecticides / Q000494:pharmacology*; D018402:Manduca / Q000201:enzymology*; D010940:Plant Proteins / Q000494:pharmacology*; D018411:Spodoptera / Q000201:enzymology; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors*
chemical_list: D057771:Cystine-Knot Miniproteins; D019476:Insect Proteins; D007306:Insecticides; D010940:Plant Proteins; D025262:Vacuolar Proton-Translocating ATPases