Single-reversal charge in the ß10-ß11 receptor-binding loop of Bacillus thuringiensis Cry4Aa and Cry4Ba toxins reflects their different toxicity against Culex spp. larvae.
Biochem Biophys Res Commun
; 450(2): 948-52, 2014 Jul 25.
Article
em En
| MEDLINE
| ID: mdl-24971536
ABSTRACT
Bacillus thuringiensis Cry4Aa toxin was previously shown to be much more toxic to Culex mosquito-larvae than its closely related toxin - Cry4Ba, conceivably due to their sequence differences within the ß10-ß11 receptor-binding loop. Here, single-Ala substitutions of five residues (Pro(510), Thr(512), Tyr(513), Lys(514) and Thr(515)) within the Cry4Aa ß10-ß11 loop revealed that only Lys(514) corresponding to the relative position of Cry4Ba-Asp(454) is crucial for toxicity against Culex quinquefasciatus larvae. Interestingly, charge-reversal mutations at Cry4Ba-Asp(454) (D454R and D454K) revealed a marked increase in toxicity against such less-susceptible larvae. In situ binding analyses revealed that both Cry4Ba-D454R and D454K mutants exhibited a significant increase in binding to apical microvilli of Culex larval midguts, albeit at lower-binding activity when compared with Cry4Aa. Altogether, our present data suggest that a positively charged side-chain near the tip of the ß10-ß11 loop plays a critical role in determining target specificity of Cry4Aa against Culex spp., and hence a great increase in the Culex larval toxicity of Cry4Ba was obtained toward an opposite-charge conversion of the corresponding Asp(454).
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Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bacillus thuringiensis
/
Proteínas de Bactérias
/
Culex
/
Endotoxinas
/
Proteínas Hemolisinas
Limite:
Animals
Idioma:
En
Revista:
Biochem Biophys Res Commun
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Tailândia