New mode of action for a knottin bioinsecticide: Pea Albumin 1 subunit b (PA1b) is the first peptidic inhibitor of V-ATPase.

Christophe Chouabe (1) , Vanessa Eyraud (2) , Pedro da Silva (2) , Isabelle Rahioui (2) , Corinne Royer (2) , Christophe Soulage (3) , Robert Bonvallet (1) , Markus Huss , Frederic Gressent (2)

1 CGPhiMC - Centre de génétique et de physiologie moléculaire et cellulaire
2 BF2I - Biologie Fonctionnelle, Insectes et Interactions
3 CarMeN - Cardiovasculaire, métabolisme, diabétologie et nutrition

PA1b (for Pea Albumin 1 subunit b) is a plant bioinsecticide lethal for several pests which are important in agriculture or human health. PA1b belongs to the inhibitory cystine knot (ICK) 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 biopesticide for pest control. Using whole-cell patch clamp techniques on Sf9 PA1b-sensible Lepidopteran insect cells, we discover that PA1b reversibly blocks ramp membrane currents in a dose dependent manner (EC50 = 0.52 uM). PA1b has the same effect as bafilomycin, a specific inhibitor of the vacuolar proton pump (V-H+-ATPase), and the PA1b-sensitive current depends on the internal proton concentration. Biochemical assays on purified V-ATPase from the Lepidopteran model Manduca sexta showed that PA1b inhibits the V1V0-H+ ATPase holoenzyme activity (IC50 ca. 70 nM), by interacting with the membrane bound V0 part of the V-ATPase. V-ATPase is a complex protein which is increasingly studied 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 paper 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 booming, since it has been demonstrated that V-ATPase plays a role in so many physiological processes.

Mots clés: PA1b

Domaines: Interactions entre organismes

Christophe Chouabe, Vanessa Eyraud, Pedro da Silva, Isabelle Rahioui, Corinne Royer, et al.. New mode of action for a knottin bioinsecticide: Pea Albumin 1 subunit b (PA1b) is the first peptidic inhibitor of V-ATPase.. Journal of Biological Chemistry, 2011, 286 (42), epub ahead of print. ⟨10.1074/jbc.M111.281055⟩. ⟨hal-00632953⟩