Activation Pattern and Toxicity of the Cry11Bb1 Toxin of Bacillus thuringiensis Subsp. Medellin

Segura, Cesar; Guzmán, Fanny; Patarroyo, Manuel E.; Ordúz, Sergio

doi:10.1006/jipa.2000.4945

Cited by 19 publications

(23 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…medellin as a 94-kDa protein composed of 782 amino acid residues (56), and its three-dimensional structure with nine ␣ helixes in the domain I has been proposed earlier (57). This protein is toxic for mosquito larvae (44, 56) after activation by mosquito larvae midgut proteases (58) and further membrane binding and permeabilization of the midgut epithelial cells (59). It has not been clear up to now which are the smallest fragments of the Cry11Bb protoxin that can permeabilize biomembranes, although Segura et al (58) proposed that the 94-kDa protoxin is activated to form 30-and 35-kDa fragments.…”

Section: Discussionmentioning

confidence: 99%

“…This protein is toxic for mosquito larvae (44, 56) after activation by mosquito larvae midgut proteases (58) and further membrane binding and permeabilization of the midgut epithelial cells (59). It has not been clear up to now which are the smallest fragments of the Cry11Bb protoxin that can permeabilize biomembranes, although Segura et al (58) proposed that the 94-kDa protoxin is activated to form 30-and 35-kDa fragments. In the case of a 70-kDa Cry11A protoxin, for instance, the coexistence of the 32-and 36-kDa fragments has been recently reported to be essential for toxicity (60).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Mitochondria Permeabilization by a Novel Polycation Peptide BTM-P1

Lemeshko

Arias

Ordúz

2005

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Bacillus thuringiensis subsp. medellin is known to produce the Cry11Bb protein of 94 kDa, which is toxic for mosquito larvae due to permeabilization of the plasma membrane of midgut epithelial cells. Earlier we found that a 2.8-kDa novel peptide BTM-P1, which was artificially synthesized taking into account the primary structure of Cry11Bb endotoxin, is active against several species of bacteria. In this work we show that BTM-P1 induces cyclosporin A-insensitive swelling of rat liver mitochondria in various salt solutions but not in the sucrose medium. Inorganic phosphate and Ca 2؉ significantly increased this effect of the peptide. The uncoupling action of BTM-P1 on oxidative phosphorylation was stronger in the potassiumcontaining media and correlated with a decrease of the inner membrane potential of mitochondria. In isotonic KNO 3 , KCl, or NH 4 NO 3 media, a complete drop of the inner membrane potential was observed at 1-2 g/ml of the peptide. The peptide-induced swelling was increased by energization of mitochondria in the potassium-containing media, but it was inhibited in the NaNO 3 , NH 4 NO 3 , and Tris-NO 3 media. All mitochondrial effects of the peptide were completely prevented by adding a single N-terminal tryptophan residue to the peptide sequence. We suggest a mechanism of membrane permeabilization that includes a transmembrane-and surface potential-dependent insertion of the polycation peptide into the lipid bilayer and its oligomerization leading to formation of ion channels and also to the mitochondrial permeability transition pore opening in a cyclosporin A-insensitive manner.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Mitochondria Permeabilization by a Novel Polycation Peptide BTM-P1

Lemeshko

Arias

Ordúz

2005

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…According to the amphiphilicity calculated with the Hoops and Woods values, the most exposed helices are α1, α2a, α2b, α3, and α6, which correspond well with the accessibility calculated with SWISSPDB, except for α1 which is packed against Domain II. It is possible that this helix has some mobility 26 . The Cry1Ab17 Domain I model agrees with data, suggesting that α4 and α5 insert into the membrane in an antiparallel manner reflecting a helical hairpin structure 15 .…”

Section: Resultsmentioning

confidence: 99%

Untitled

Kashyap¹,

Singh²,

Amla³

2010

ScienceAsia

View full text Add to dashboard Cite

ABSTRACT:We predict the first theoretical structural model of the newly reported Cry1Ab17 δ-endotoxin produced by Bacillus thuringiensis using homology modelling. Both Cry1Ab17 and Cry1Aa share a common structure; both contain three flexible domains that participate in the formation of a pore and determine the receptor binding specificity. The main differences between the two is in the length of loops, and in Cry1Ab17, the absence of α7b, α10a, α10b, α12a, β19, β20 and presence of additional β0 β1b, α9b components. A few of the components such as α8a, α8b, α9a, α9b, and α11a differ in their locations. A better understanding of the 3-D structure of Cry1Ab17 will be helpful in designing the domain swapping experiments to improve its insecticidal toxicity.

show abstract

“…According to the amphiphilicity calculated with the Hoops and Woods values, the most exposed helices are α1, α2a, α2b, α3 and α6, which corresponds well with the accessibility calculated with SwissPDB, except for α1, which is packed against domain II. It is possible that this helix will have some mobility, if we take into consideration that one of the cutting sites by gut proteases is located between Ser56 and Ile58, close to the middle of this helix (Segura et al 2000). The charge distribution pattern in the Cry11Bb theoretical model corresponds to a negatively charged patch along ß4 and ß13 of domains II and III respectively.…”

Section: Discussionmentioning

confidence: 99%