This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chow, E Articles by Gill, S S Search for Related Content PubMed PubMed Citation Articles by Chow, E Articles by Gill, S S Agricola Articles by Chow, E Articles by Gill, S S

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1989 November; 55(11): 2779-2788

Binding and aggregation of the 25-kilodalton toxin of Bacillus thuringiensis subsp. israelensis to cell membranes and alteration by monoclonal antibodies and amino acid modifiers.

E Chow, G J Singh and S S Gill

Department of Entomology, University of California, Riverside 92521.

ABSTRACT

The 25-kilodalton toxin of Bacillus thuringiensis subsp. israelensis binds irreversibly to Aedes albopictus cells, Choristoneura fumiferana cells, and erythrocytes. The binding to cells increased with both toxin concentration and time and when the cells were first preincubated with unlabeled toxin. Binding data indicated a two- to threefold increase in the rate of binding after the amount of the membrane-bound toxin reached approximately 3.5 fmol/3 x 10(5) A. albopictus cells or 3.3. fmol/2 x 10(5) C. fumiferana cells. When this level of bound toxin was reached, the toxins also began forming aggregates at the cell membrane. The toxin aggregates were extracted with 10% Triton X-100 and separated from the monomers with a 5 to 20% sucrose density gradient. The toxin aggregates isolated from A. albopictus and C. fumiferana cell membranes were ca. 400 kilodaltons, while those isolated from human erythrocytes were significantly smaller. The proportion of the toxin found in aggregate form increased rapidly with the amount of toxin bound; however, the molecular size of the aggregates remained constant. Eleven monoclonal antibodies raised against the native form of the toxin blocked 80 to 97% of the toxin binding to cells. The epitope of one of these monoclonal antibodies was mapped to a domain which included the cysteine, suggesting the importance of the domain around this amino acid to binding. Toxin binding and cell lysis were also inhibited by treating the toxin with HgCl2, further indicating the importance of the C-terminal hydrophobic cysteine-containing domain in cytolytic activity of the 25-kilodalton protein.

---

Appl Environ Microbiol. 1989 November; 55(11): 2779-2788

This article has been cited by other articles:

• Cahan, R., Friman, H., Nitzan, Y. (2008). Antibacterial activity of Cyt1Aa from Bacillus thuringiensis subsp. israelensis. Microbiology 154: 3529-3536 [Abstract] [Full Text]  
• Oestergaard, J., Ehlers, R.-U., Martinez-Ramirez, A. C., Real, M. D. (2007). Binding of Cyt1Aa and Cry11Aa Toxins of Bacillus thuringiensis Serovar israelensis to Brush Border Membrane Vesicles of Tipula paludosa (Diptera: Nematocera) and Subsequent Pore Formation. Appl. Environ. Microbiol. 73: 3623-3629 [Abstract] [Full Text]  
• Itsko, M., Manasherob, R., Zaritsky, A. (2005). Partial Restoration of Antibacterial Activity of the Protein Encoded by a Cryptic Open Reading Frame (cyt1Ca) from Bacillus thuringiensis subsp. israelensis by Site-Directed Mutagenesis. J. Bacteriol. 187: 6379-6385 [Abstract] [Full Text]  
• Butko, P. (2003). Cytolytic Toxin Cyt1A and Its Mechanism of Membrane Damage: Data and Hypotheses. Appl. Environ. Microbiol. 69: 2415-2422 [Full Text]  
• Aronson, A. I., Geng, C., Wu, L. (1999). Aggregation of Bacillus thuringiensis Cry1A Toxins upon Binding to Target Insect Larval Midgut Vesicles. Appl. Environ. Microbiol. 65: 2503-2507 [Abstract] [Full Text]  
• Schnepf, E., Crickmore, N., Van Rie, J., Lereclus, D., Baum, J., Feitelson, J., Zeigler, D. R., Dean, D. H. (1998). Bacillus thuringiensis and Its Pesticidal Crystal Proteins. Microbiol. Mol. Biol. Rev. 62: 775-806 [Abstract] [Full Text]  
• Gill, S. S., Cowles, E. A., Francis, V. (1995). Identification, Isolation, and Cloning of a Bacillus thuringiensis CryIAc Toxin-binding Protein from the Midgut of the Lepidopteran Insect Heliothis virescens. J. Biol. Chem. 270: 27277-27282 [Abstract] [Full Text]