We have examined the type of inhibition exerted by an activated preparation of the Bacillus thuringiensis delta-endotoxin CrylAa on K+-dependent leucine transport into midgut brush border membrane vesicles or epithelial cells of the isolated midgut from Bombyx mori to study its possible interaction with the amino acid symporter. K+ permeability and the cation-dependent amino acid translocation into brush border membrane vesicles were evaluated by monitoring the fluorescence of the voltage-sensitive cyanine dye 3,3'-dipropylthiadicarbocyanine iodide. The symporter ability to accept Na+ instead of K+ was exploited and the dissipation of an imposed inside-negative potential (K+ gradient in>out and valinomycin) was registered in the presence of a Na+ gradient (out>in) and of the amino acid. The fluorescence quenching dissipated more rapidly when the amino acid was present. Preincubation of brush border membrane vesicles with CrylAa caused a significant decrease of the amino acid-dependent recovery of fluorescence, whereas K+ permeability was sparely affected. In the isolated midgut, CrylAa inhibits leucine uptake as well as the transepithelial electrical potential difference. The strong inhibition exerted by the delta-endotoxin was observed also in the absence of potassium and the transepithelial electrical potential difference. The results obtained strongly suggest a direct interaction of CrylAa delta-endotoxin with the K+/amino acid symporter.
Bacillus thuringiensis CrylAa δ-endotoxin affects the K+/amino acid symport in Bombyx mori larval midgut / M.G. Leonardi, P. Parenti, M. Casartelli, B. Giordana. - In: THE JOURNAL OF MEMBRANE BIOLOGY. - ISSN 0022-2631. - 159:3(1997), pp. 209-217.
|Titolo:||Bacillus thuringiensis CrylAa δ-endotoxin affects the K+/amino acid symport in Bombyx mori larval midgut|
|Parole Chiave:||CrylAa delta-endotoxin ; Bacillus thuringiensis ; Bombyx mori larval midgut ; K+/amino acid symporters ; Brush border membrane vesicles ; Isolated midgut|
|Settore Scientifico Disciplinare:||Settore BIO/09 - Fisiologia|
|Data di pubblicazione:||1997|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1007/s002329900284|
|Appare nelle tipologie:||01 - Articolo su periodico|