New Mode of Action for a Knottin Protein Bioinsecticide PEA ALBUMIN 1 SUBUNIT b (PA1b) IS THE FIRST PEPTIDIC INHIBITOR OF V-ATPase
Autor(en): | Chouabe, Christophe Eyraud, Vanessa Da Silva, Pedro Rahioui, Isabelle Royer, Corinne Soulage, Christophe Bonvallet, Robert Huss, Markus Gressent, Frederic |
Stichwörter: | BINDING-SITE; Biochemistry & Molecular Biology; BIOLOGICAL-ACTIVITY; CELLS; CYCLOTIDES; ENTOMOTOXIN; PEA-SEEDS; PLASMA-MEMBRANE; PURIFICATION; V-ATPASES; WEEVIL SITOPHILUS | Erscheinungsdatum: | 2011 | Herausgeber: | AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC | Journal: | JOURNAL OF BIOLOGICAL CHEMISTRY | Volumen: | 286 | Ausgabe: | 42 | Startseite: | 36291 | Seitenende: | 36296 | Zusammenfassung: | 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 (EC50 = 0.52 mu M). 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 V1V0-type H+-ATPase holoenzyme activity (IC50 similar to 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. |
DOI: | 10.1074/jbc.M111.281055 |
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