SciELO - Scientific Electronic Library Online

 
vol.95 número5Posterior spiracles of fourth instar larvae of four species of phlebotomine sand flies (Diptera: Psychodidae) under scanning electron microscopyChitinolytic activity in viable spores of encephalitozoon species índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Revista

Articulo

Indicadores

Links relacionados

Compartir


Memórias do Instituto Oswaldo Cruz

versión impresa ISSN 0074-0276versión On-line ISSN 1678-8060

Resumen

ESCOBAR, Elizabeth et al. Proteolytic processing of the Cyt1Ab1 toxin produced by Bacillus thuringiensis subsp. medellin. Mem. Inst. Oswaldo Cruz [online]. 2000, vol.95, n.5, pp.693-700. ISSN 0074-0276.  http://dx.doi.org/10.1590/S0074-02762000000500014.

Bacillus thuringiensis produces d-endotoxins that require proteolytic processing to become active. The activation of the B. thuringiensis subsp. medellin 28 kDa (Cyt1Ab1) cytolytic toxin by trypsin, chymotrypsin and gut extract from Culex quinquefasciatus larvae was analyzed. The Cyt1Ab1 toxin of B. thuringiensis subsp. medellin was processed by all proteases tested to fragments between 23 and 25 kDa, while processing of the Cyt1Aa1 toxin produce fragments between 22.5 and 24.5 kDa. The Cyt1Ab1 toxin was preferentially processed at the alkaline pH of 12. The in vitro proteolytic processing of the Cyt1Ab1 toxin by C. quinquefasciatus larvae midgut extract showed a 25 kDa fragment; a similar result was observed when the activation was performed in the in vivo experiments. The solubilized Cyt1Ab1 toxin and the protease resistant cores generated by in vitro processing showed hemolytic activity but not mosquitocidal activity. Amino terminal sequence of the C. quinquefasciatus gut extract resistant fragment indicated that the cutting site was located between Lys31 and Asp32, with a sequence DDPNEKNNHNS; while for the trypsin-resistant fragment the cutting site was determined between Leu29 and Arg30, and for the chymotrypsin-resistant fragment between Arg30 and Lys31.

Palabras clave : Bacillus thuringiensis; Cyt1Ab1; cytolytic; hemolytic; proteolytic processing; midgut proteases.

        · texto en Inglés     · Inglés ( pdf )

 

Creative Commons License Todo el contenido de esta revista, excepto dónde está identificado, está bajo una Licencia Creative Commons