Bacillus thuringiensis Cyt2Aa2 binding on lipid/cholesterol bilayer depends on protein concentration and time.
Biochem Biophys Res Commun
; 492(2): 212-217, 2017 10 14.
Article
en En
| MEDLINE
| ID: mdl-28821431
ABSTRACT
Bacillus thuringiensis produces cytolytic proteins (Cyt) that show toxicity against dipteran insect larvae acting directly on the cell membrane. Up to now, two different models have been proposed to explain the interaction mechanism of the cytolytic protein Cyt2Aa2 on lipid membranes pore-forming and detergent-like action. Here we report on the interaction of Cyt2Aa2 with lipid/cholesterol bilayers at early stage (far from equilibrium) as a function of protein concentration. Quartz crystal microbalance with dissipation (QCM-D) measurements showed that the rate of protein adsorption increased with concentration, although the mass of the final protein-lipid was similar after two hours. In addition, the dissipation (compliance of the hybrid lipid/protein layer) increased with decreasing protein concentration. Furthermore, atomic force microscopy (AFM) revealed that the structure of the protein-lipid layer was concentration and time dependent. A rigid hybrid homogeneous layer was observed at protein concentrations of 50 µg/ml and 100 µg/ml after 30 min. At lower concentrations, 10 µg/ml and 17.5 µg/ml, protein adsorption on the lipid layer led to the formation of small aggregates. Interestingly, at 25 µg/ml a transition of a hole-like structure into a homogeneous layer was observed. This suggests that 25 µg/ml is a threshold concentration for the binding mechanism of Cyt2Aa2 on to lipid membranes.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bacillus thuringiensis
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Proteínas Bacterianas
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Colesterol
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Endotoxinas
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Proteínas Hemolisinas
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Membrana Dobles de Lípidos
Idioma:
En
Revista:
Biochem Biophys Res Commun
Año:
2017
Tipo del documento:
Article