Phylogenetic relationships of Bacillus thuringiensis delta-endotoxin family proteins and their functional domains

Bravo, Alejandra

doi:10.1128/jb.179.9.2793-2801.1997

Cited by 130 publications

(95 citation statements)

References 48 publications

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“…Domain II of Cry1Dc, the most variable domain according to previous reports 37 , was found to be relatively conserved (8.3% amino acid substitutions) between the Cry1D-type protein examined in the present study. The observed conservation of Domain II between the Cry1D-type proteins emphasizes its importance in specific receptor binding 38,39 .…”

Section: Discussionsupporting

confidence: 69%

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Lertwiriyawong¹,

Pinthong²,

Chanpaisaeng³

et al. 2010

ScienceAsia

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ABSTRACT:The novel δ-endotoxin from Bacillus thuringiensis (Bt) is one of the alternative measures for lepidopteran pest control. A survey of 31 Bt isolates, obtained from Thailand and previously screened for their toxicity to lepidopterans, was conducted to determine the presence of cry1-type genes, using polymerase chain reaction -restriction fragment length polymorphism analysis. Seven distinct types of cry1 genes: cry1Aa, cry1B, cry1C, cry1Cb, cry1D, cry1E, and cry1F, were identified. The most common of the cry1-type genes was cry1Cb, followed by cry1C and cry1D, which covered 64.6, 48.4, and 25.8%, respectively. Besides cry1C and cry1Cb, two candidate cry genes, cry1E and cry1D, of isolate JC 190 (harbouring cry1C/1E), with cotton bollworm toxin specificity, showed 99% amino acid sequence identity to Cry1Ea of B. thuringiensis subsp. kenyae, while isolate JC 291 (containing cry1C/1Cb/1D), with Asian corn borer toxin specificity, harboured Cry1Dc, which exhibited only 84% amino acid sequence identity to Cry1Da of B. thuringiensis subsp. aizawai. The C-terminus of the JC291Cry1Dc possessed a unique sequence, 812-NVPIIPIISPW-822. Furthermore, the major differences between the 3D structure of Cry1Dc and Cry1Aa were confined to Domain II as three loop structures.

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Section: Discussionsupporting

confidence: 69%

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Lertwiriyawong¹,

Pinthong²,

Chanpaisaeng³

et al. 2010

ScienceAsia

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“…In Cry1Aa, domains I and II are linked by four salt bridges: Asp , are also found in Cry3A (6,7). In addition, for all four salt bridges at least one of the amino acid residues forming the bridge is located within block 2, a sequence that is highly conserved among Cry toxins (1,5,36). However, only in the case of the Asp 242 -Arg 265 salt bridge are both amino acids located within block 2 ( Fig.…”

mentioning

confidence: 92%

Role of Interdomain Salt Bridges in the Pore-forming Ability of the Bacillus thuringiensis Toxins Cry1Aa and Cry1Ac

Coux¹,

Vachon²,

Rang³

et al. 2001

Journal of Biological Chemistry

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linking domains I and II in Cry1Aa were abolished individually in ␣-helix 7 mutants D222A, R233A, R234A, and D242A. Two additional mutants targeting the fourth salt bridge (R265A) and the double mutant (D242A/R265A) were rapidly degraded during trypsin activation. Mutations were also introduced in the corresponding Cry1Ac salt bridge (D242E, D242K, D242N, and D242P), but only D242N and D242P could be produced. All toxins tested, except D242A, were shown by light-scattering experiments to permeabilize Manduca sexta larval midgut brush border membrane vesicles. The three active Cry1Aa mutants at pH 10.5, as well as D222A at pH 7.5, demonstrated a faster rate of pore formation than Cry1Aa, suggesting that increases in molecular flexibility due to the removal of a salt bridge facilitated toxin insertion into the membrane. However, all mutants were considerably less toxic to M. sexta larvae than to the respective parental toxins, suggesting that increased flexibility made the toxins more susceptible to proteolysis in the insect midgut. Interdomain salt bridges, especially the Asp 242 -Arg 265 bridge, therefore contribute greatly to the stability of the protein in the larval midgut, whereas their role in intrinsic pore-forming ability is relatively less important.During sporulation, Bacillus thuringiensis produces a parasporal crystal body composed of one or more proteins that are toxic to a number of insect larvae (1) or to other invertebrates (2). After solubilization in the insect midgut and activation by intestinal proteases, these proteins bind to specific receptors at the surface of the apical brush border membrane of epithelial columnar cells, insert into the membrane, and form pores that disrupt midgut cellular functions (3-5).Elucidation of the crystal structure of the coleopteranspecific Cry3A toxin (6) and the lepidopteran-specific Cry1Aa toxin (7) revealed a similar three-domain structure for both proteins. Domain I, composed of eight amphipathic ␣-helices, is thought to be involved in membrane insertion and pore formation (8 -15). Domain II, composed of three ␤-sheets and two short ␣-helices, is involved in the binding of the toxin to its receptor on the epithelial cell surface (16 -23). Domain III, composed of two ␤-sheets forming a face-to-face ␤-sandwich, appears to be involved in the stability (6), specificity (24 -26), and binding (27-34) of the toxin.These domains are closely packed together with the largest number of interdomain contacts found between domains I and II (6, 7). In Cry1Aa, domains I and II are linked by four salt bridges: Asp

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“…Preparations of bacterial spores and crystalline proteins are widely used as Bt insecticides for the control of insect pests of crops. Bttoxins are classified based on their specific activity against invertebrates [11][12][13][14]. Cry1Ab is a toxin commonly used against the European corn borer (Ostrinia nubilalis Hü bner) and can be produced either as a full-length protoxin, as by Monsanto, or as the Novartis-produced, truncated, preactivated toxin.…”

Section: Introductionmentioning

confidence: 99%

Can Transgenic Maize Affect Soil Microbial Communities?

Mulder¹,

Wouterse²,

Raubuch³

et al. 2005

PLoS Comp Biol

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The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short Bt-induced ecological shifts in the microbial communities of croplands' soils.

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Phylogenetic relationships of Bacillus thuringiensis delta-endotoxin family proteins and their functional domains

Cited by 130 publications

References 48 publications

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Role of Interdomain Salt Bridges in the Pore-forming Ability of the Bacillus thuringiensis Toxins Cry1Aa and Cry1Ac

Can Transgenic Maize Affect Soil Microbial Communities?

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