Mode of Action of Cry Toxins from Bacillus thuringiensis and Resistance Mechanisms

2018 ◽  
pp. 15-27 ◽  
Author(s):  
Mario Soberón ◽  
Rose Monnerat ◽  
Alejandra Bravo
Keyword(s):  
Bacillus Thuringiensis ◽  
Mode Of Action ◽  
Resistance Mechanisms ◽  
Cry Toxins

scholarly journals Employing phage display to study the mode of action of Bacillus thuringiensis Cry toxins

Peptides ◽  
2008 ◽  
Vol 29 (2) ◽  
pp. 324-329 ◽  
Author(s):  
Luisa Elena Fernández ◽  
Isabel Gómez ◽  
Sabino Pacheco ◽  
Iván Arenas ◽  
Sarjeet S. Gilla ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Phage Display ◽  
Mode Of Action ◽  
Cry Toxins

scholarly journals Key Residues of Bacillus Thuringiensis Cry2Ab for Oligomerization and Pore-Formation Activity

2021 ◽  
Author(s):  
Zhi-Zhen Pan ◽  
Lian Xu ◽  
Bo Liu ◽  
Qing-Xi Chen ◽  
Yu-Jing Zhu
Keyword(s):  
Bacillus Thuringiensis ◽  
Insecticidal Activity ◽  
Mode Of Action ◽  
Pore Formation ◽  
Wild Type ◽  
Cry Toxins ◽  
Key Residues ◽  
Domain I ◽  
First Time

Abstract As a pore-forming toxin, oligomerization and pore-formation were both required for the mode of action of Cry toxins. Previous studies revealed that Domain I helices α4-α5 were involved in oligomerization of Cry2Ab, while the active residues in charge of Cry2Ab aggregation remained ambiguous. In present studies, we built 20 Cry2Ab alanine mutants site directed in helices α4-α5 and demonstrated that mutants N151A, T152A, F157A, L183A, L185A and I188A blocked the assembly of 250 kDa oligomers, suggesting that those residues were key residues for Cry2Ab oligomerization. As expected, those variants severely reduced the insecticidal activity against P. xylostella which was similar to our previous reports. Furthermore, we found that the pore-forming activities of non-oligomerization mutants sharply decreased compared to wild-type Cry2Ab. Taken together, our data comprehensively identified key residues for Cry2Ab for the first time and emphasized that oligomerization was closely related to insecticidal activity and pore-forming activity in Cry2Ab.

scholarly journals Key residues of Bacillus thuringiensis Cry2Ab for oligomerization and pore-formation activity

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhi-Zhen Pan ◽  
Lian Xu ◽  
Bo Liu ◽  
Qing-Xi Chen ◽  
Yu-Jing Zhu
Keyword(s):  
Bacillus Thuringiensis ◽  
Insecticidal Activity ◽  
Mode Of Action ◽  
Pore Formation ◽  
Wild Type ◽  
Cry Toxins ◽  
Key Residues ◽  
Domain I

AbstractAs a pore-forming toxin, activation, oligomerization and pore-formation were both required for the mode of action of Cry toxins. Previous results revealed that the helices α4–α5 of Domain I were involved in the oligomerization of Cry2Ab, however, the key residues for Cry2Ab aggregation remained ambiguous. In present studies, we built 20 Cry2Ab alanine mutants site-directed in the helices α4–α5 of Domain I and demonstrated that mutants N151A, T152A, F157A, L183A, L185A and I188A could reduce the assembly of the 250 kDa oligomers, suggesting that these mutation residues might be essential for Cry2Ab oligomerization. As expected, all of these variants showed lower insecticidal activity against P. xylostella. Furthermore, we found that the pore-forming activities of these mutants also decreased when compared to wild-type Cry2Ab. Taken together, our data identified key residues for Cry2Ab oligomerization and emphasized that oligomerization was closely related to the insecticidal activity and pore-forming activity of Cry2Ab.

scholarly journals An Intramolecular Salt Bridge in Bacillus thuringiensis Cry4Ba Toxin Is Involved in the Stability of Helix α-3, Which Is Needed for Oligomerization and Insecticidal Activity

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Sabino Pacheco ◽  
Isabel Gómez ◽  
Jorge Sánchez ◽  
Blanca-Ines García-Gómez ◽  
Mario Soberón ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Double Point ◽  
Single Point ◽  
Three Dimensional ◽  
Point Mutations ◽  
Salt Bridge ◽  
Dimensional Structure ◽  
Cry Toxins ◽  
Content Type ◽  
Domain I

ABSTRACT Bacillus thuringiensis three-domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intramolecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity. These mutants were also altered in oligomerization, and the mutant K115D was more sensitive to protease digestion. The double point mutant with reversed charges, D111K-K115D, recovered both oligomerization and toxicity, suggesting that this salt bridge is highly important for conservation of the structure of helix α-3 and necessary to promote the correct oligomerization of the toxin. IMPORTANCE Domain I has been shown to be involved in oligomerization through helix α-3 in different Cry toxins, and mutations affecting oligomerization also elicit changes in toxicity. The three-dimensional structure of the Cry4Ba toxin reveals an intramolecular salt bridge in helix α-3 of domain I. Mutations that disrupt this salt bridge resulted in changes in Cry4Ba oligomerization and toxicity, while a double point reciprocal mutation that restored the salt bridge resulted in recovery of toxin oligomerization and toxicity. These data highlight the role of oligomer formation as a key step in Cry4Ba toxicity.

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