ß/δ-PrIT1, a highly insecticidal toxin from the venom of the Brazilian spider Phoneutria reidyi (F.O. Pickard-Cambridge, 1897).
Toxicon
; 104: 73-82, 2015 Sep 15.
Article
en En
| MEDLINE
| ID: mdl-26220799
ABSTRACT
A potent insecticidal toxin, ß/δ-PrIT1, molecular mass of 5598.86 [M+H](+), was characterized from Phoneutria reidyi spider venom. Its partial amino acid sequence showed high similarity with insecticidal spider toxins from the genus Phoneutria. ß/δ-PrIT1 was very toxic (LD50 = 4 nmol/g) to flies (Musca domestica), but not to mice (Mus musculus). Kinetic studies showed that (125)I-ß/δ-PrIT1 binds to two distinct sites in insect sodium channels, with close affinity (Kd1 = 34.7 pM and Kd2 = 35.1 pM). Its association is rather fast (t1/2(1) = 1.4 min, t1/2(2) = 8.5 min) and its dissociation is a slower process (t1/2(1) = 5.4 min, t1/2(2) = 32.8 min). On rat brain synaptosomes ß/δ-PrIT1 partially competed (â¼30%) with the beta-toxin (125)I-CssIV, but did not compete with the alpha-toxin of reference (125)I-AaII, nor with the beta-toxin (125)I-TsVII. On cockroach nerve cord synaptosomes, ß/δ-PrIT1 did not compete with the anti-insect toxin (125)I-LqqIT1, but it competed (IC50 = 80 pM) with the "alpha-like" toxin (125)I-BomIV. In cockroach neurons, ß/δ-PrIT1 inhibited the inactivation of Nav-channels and it shifted the sodium channel activation to hyperpolarizing potentials. These results indicate two different binding sites for ß/δ-PrIT1, leading to two different pharmacological responses. ß/δ-PrIT1 is one of the most toxic spider toxins to insects without apparent toxicity to mammals, and provide new model for the development of insecticides.
Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Venenos de Araña
/
Arañas
/
Sinaptosomas
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Insecticidas
Tipo de estudio:
Prognostic_studies
Límite:
Animals
País/Región como asunto:
America do sul
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Brasil
Idioma:
En
Revista:
Toxicon
Año:
2015
Tipo del documento:
Article
País de afiliación:
Brasil