scholarly journals Specific binding of Bacillus thuringiensis Cry1Ea toxin, and Cry1Ac and Cry1Fa competition analyses in Anticarsia gemmatalis and Chrysodeixis includens

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yolanda Bel ◽  
Marc Zack ◽  
Ken Narva ◽  
Baltasar Escriche
Keyword(s):  
Bacillus Thuringiensis ◽  
Brush Border ◽  
Binding Sites ◽  
Brush Border Membrane ◽  
Specific Binding ◽  
Anticarsia Gemmatalis ◽  
Binding Studies ◽  
Velvetbean Caterpillar ◽  
Competition Binding ◽  
Chrysodeixis Includens

AbstractAnticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper) are two important defoliation pests of soybeans. In the present study, we have investigated the susceptibility and brush border membrane-binding properties of both species to Bacillus thuringiensis Cry1Ea toxin. Bioassays performed in first-instar larvae demonstrated potent activity against both soybean pests in terms of mortality or practical mortality. Competition-binding studies carried out with 125Iodine-labelled Cry1Ea, demonstrated the presence of specific binding sites on the midgut brush border membrane vesicles (BBMV) of both insect species. Heterologous competition-binding experiments indicated that Cry1Ea does not share binding sites with Cry1Ac or Cry1Fa in either soybean pest. This study contributes to the knowledge of Cry1Ea toxicity and midgut binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ea with other Bt proteins aimed at controlling lepidopteran pests in soybeans.

scholarly journals Toxicity and Binding Studies of Bacillus thuringiensis Cry1Ac, Cry1F, Cry1C, and Cry2A Proteins in the Soybean Pests Anticarsia gemmatalis and Chrysodeixis (Pseudoplusia) includens

2017 ◽  
Vol 83 (11) ◽  
Author(s):  
Yolanda Bel ◽  
Joel J. Sheets ◽  
Sek Yee Tan ◽  
Kenneth E. Narva ◽  
Baltasar Escriche
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Sites ◽  
Specific Binding ◽  
Management Strategies ◽  
Anticarsia Gemmatalis ◽  
Cross Resistance ◽  
Binding Studies ◽  
Content Type ◽  
Bt Toxins ◽  
Competition Binding

ABSTRACT Anticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper, formerly named Pseudoplusia includens) are two important defoliating insects of soybeans. Both lepidopteran pests are controlled mainly with synthetic insecticides. Alternative control strategies, such as biopesticides based on the Bacillus thuringiensis (Bt) toxins or transgenic plants expressing Bt toxins, can be used and are increasingly being adopted. Studies on the insect susceptibilities and modes of action of the different Bt toxins are crucial to determine management strategies to control the pests and to delay outbreaks of insect resistance. In the present study, the susceptibilities of both soybean pests to the Bt toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa have been investigated. Bioassays performed in first-instar larvae showed that both insects are susceptible to all these toxins. Competition-binding studies carried out with Cry1Ac and Cry1Fa 125-iodine labeled proteins demonstrated the presence of specific binding sites for both of them on the midgut brush border membrane vesicles (BBMVs) of both A. gemmatalis and C. includens. Competition-binding experiments and specific-binding inhibition studies performed with selected sugars and lectins indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites in the midguts of both insects. Also, the Cry1Ac- or Cry1Fa-binding sites were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity and midgut toxin binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops. IMPORTANCE In the present study, the toxicity and the mode of action of the Bacillus thuringiensis (Bt) toxins Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa in Anticarsia gemmatalis and Chrysodeixis includens (important defoliating pests of soybeans) have been investigated. These studies are crucial for determining management strategies for pest control. Bioassays showed that both insects were susceptible to the toxins. Competition-binding studies demonstrated the presence of Cry1Fa- and Cry1Ac-specific binding sites in the midguts of both pests. These results, together with the results from binding inhibition studies performed with sugars and lectins, indicated that Cry1Ac and Cry1Fa share some, but not all, binding sites, and that they were not shared with Cry1Ca or Cry2Aa in either soybean pest. This study contributes to the knowledge of Bt toxicity in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ac, Cry1Fa, Cry1Ca, and Cry2Aa Bt proteins as candidate proteins for Bt-pyramided crops.

Critical domains in the specific binding of radiolabelled Vip3Af insecticidal protein to brush border membrane vesicles from Spodoptera spp. and cultured insect cells

2021 ◽  
Author(s):  
Yudong Quan ◽  
Maria Lázaro-Berenguer ◽  
Patricia Hernández-Martínez ◽  
Juan Ferré
Keyword(s):  
Brush Border ◽  
Binding Sites ◽  
Brush Border Membrane ◽  
Ex Vivo ◽  
Specific Binding ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Cry Proteins ◽  
Competition Binding

Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis have been used, in combination with Cry proteins, to better control insect pests and as a strategy to delay the evolution of resistance to Cry proteins in Bt crops (crops protected from insect attack by the expression of proteins from B. thuringiensis ). In this study, we have set up the conditions to analyze the specific binding of 125 I-Vip3Af to Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). Heterologous competition binding experiments revealed that Vip3Aa shares the same binding sites with Vip3Af, but that Vip3Ca does not recognize all of them. As expected, Cry1Ac and Cry1F did not compete for Vip3Af binding sites. By trypsin treatment of selected alanine-mutants, we were able to generate truncated versions of Vip3Af. Their use as competitors with 125 I-Vip3Af indicated that only those molecules containing domains I to III (DI-III and DI-IV) were able to compete with the trypsin-activated Vip3Af protein for binding, and that molecules only containing either domain IV or domains IV and V (DIV and DIV-V) were unable to compete with Vip3Af. These results were further confirmed with competition binding experiments using 125 I-DI-III. In addition, the truncated protein 125 I-DI-III also bound specifically to Sf21 cells. Cell viability assays showed that the truncated proteins DI-III and DI-IV were as toxic to Sf21 cells as the activated Vip3Af, suggesting that domains IV and V are not necessary for the toxicity to Sf21 cells, in contrast to their requirement in vivo. IMPORTANCE This study shows that Vip3Af binding sites are fully shared with Vip3Aa, only partially shared with Vip3Ca, and not shared with Cry1Ac and Cry1F in two Spodoptera spp. Truncated versions of Vip3Af revealed that only domains I to III were necessary for the specific binding, most likely because they can form the functional tetrameric oligomer and because domain III is supposed to contain the binding epitopes. In contrast to results obtained in vivo (bioassays against larvae), domains IV and V are not necessary for the ex vivo toxicity to Sf21 cells.

scholarly journals Binding Sites for Bacillus thuringiensis Cry2Ae Toxin on Heliothine Brush Border Membrane Vesicles Are Not Shared with Cry1A, Cry1F, or Vip3A Toxin

2011 ◽  
Vol 77 (10) ◽  
pp. 3182-3188 ◽  
Author(s):  
C. Gouffon ◽  
A. Van Vliet ◽  
J. Van Rie ◽  
S. Jansens ◽  
J. L. Jurat-Fuentes
Keyword(s):  
Bacillus Thuringiensis ◽  
Brush Border ◽  
Binding Sites ◽  
Brush Border Membrane ◽  
Specific Binding ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Target Range ◽  
Content Type ◽  
Bt Toxins

ABSTRACTThe use of combinations ofBacillus thuringiensis(Bt) toxins with diverse modes of action for insect pest control has been proposed as the most efficient strategy to increase target range and delay the onset of insect resistance. Considering that most cases of cross-resistance to Bt toxins in laboratory-selected insect colonies are due to alteration of common toxin binding sites, independent modes of action can be defined as toxins sharing limited or no binding sites in brush border membrane vesicles (BBMV) prepared from the target insect larvae. In this paper, we report on the specific binding of Cry2Ae toxin to binding sites on BBMV from larvae of the three most commercially relevant heliothine species,Heliothis virescens,Helicoverpa zea, andHelicoverpa armigera. Using chromatographic purification under reducing conditions before labeling, we detected specific binding of radiolabeled Cry2Ae, which allowed us to perform competition assays using Cry1Ab, Cry1Ac, Cry1Fa, Vip3A, Cry2Ae, and Cry2Ab toxins as competitors. In these assays, Cry2Ae binding sites were shared with Cry2Ab but not with the tested Cry1 or Vip3A toxins. Our data support the use of Cry2Ae toxin in combination with Cry1 or Vip3A toxins in strategies to increase target range and delay the onset of heliothine resistance.

scholarly journals Lepidopteran-Active Variable-Region Sequence Imparts Coleopteran Activity in eCry3.1Ab, an Engineered Bacillus thuringiensis Hybrid Insecticidal Protein

2010 ◽  
Vol 76 (10) ◽  
pp. 3082-3088 ◽  
Author(s):  
Frederick S. Walters ◽  
Cheryl M. deFontes ◽  
Hope Hart ◽  
Gregory W. Warren ◽  
Jeng S. Chen
Keyword(s):  
Bacillus Thuringiensis ◽  
Brush Border ◽  
Specific Binding ◽  
Variable Region ◽  
Diabrotica Virgifera Virgifera ◽  
Pest Species ◽  
Binding Studies ◽  
Active Protein ◽  
Molar Excess ◽  
Domain Iii

ABSTRACT A unique, coleopteran-active protein, termed eCry3.1Ab, was generated following variable-region exchange of a Bacillus thuringiensis lepidopteran-active protein, Cry1Ab, with a Cry3A region. Our results support the hypothesis that this variable-region exchange is responsible for imparting strong bioactivity against the larvae of western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte), a pest species which is not susceptible to either parent protein sequence. This study demonstrates the potential of successfully engineering a portion(s) of a lepidopteran-active B. thuringiensis sequence so that it has activity against coleopterans. Further elucidation of the eCry3.1Ab activity indicated the importance of variable regions 4 to 6 that were derived from Cry1Ab instead of Cry1Ac. There was some flexibility in making domain III of engineered hybrid insecticidal proteins even more Cry1Ab-like and retaining activity, while there was less flexibility in making domain III more Cry3A-like and retaining activity. In vitro binding studies with brush border membrane vesicles demonstrated that there was specific binding of chymotrypsin-processed modified Cry3A (mCry3A), which was not diminished by addition of a 100-fold molar excess of chymotrypsin-processed eCry3.1Ab or unprocessed eCry3.1Ab. In addition, in the converse experiment, specific binding of chymotrypsin-processed eCry3.1Ab was not diminished by the presence of a 75-fold molar excess of chymotrypsin-processed mCry3A. These data support the hypothesis that eCry3.1Ab can interact with different binding sites than the activated form of mCry3A in the WCR brush border and may provide a different mode of action from the standpoint of resistance management.

scholarly journals Binding of Bacillus thuringiensis Cry1 Toxins to the Midgut Brush Border Membrane Vesicles of Chilo suppressalis (Lepidoptera: Pyralidae): Evidence of Shared Binding Sites

1996 ◽  
Vol 62 (8) ◽  
pp. 3073-3073
Author(s):  
L Fiuza ◽  
C Nielsen-Leroux ◽  
E Goze ◽  
R Frutos ◽  
J Charles
Keyword(s):  
Bacillus Thuringiensis ◽  
Brush Border ◽  
Binding Sites ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Chilo Suppressalis ◽  
Lepidoptera Pyralidae

Volume 62, no. 5, p. 1544, Abstract, line 4: "Cry1Aa" should read "Cry1Ac." [This corrects the article on p. 1544 in vol. 62.].

scholarly journals Transcortin interaction with human syncytiotrophoblast

1994 ◽  
Vol 40 (5) ◽  
pp. 41-44
Author(s):  
Ye. P. Kiselyova ◽  
I. I. Vashkevich ◽  
O. A. Strelchenok
Keyword(s):  
Pregnant Women ◽  
Brush Border ◽  
Binding Sites ◽  
Brush Border Membrane ◽  
Specific Binding ◽  
Hormonal Effects ◽  
Corticosteroid Binding Globulin

Interactions of transcortin (corticosteroid-binding globulin, CBG) variants, nCBG and rCBG, present in the blood of pregnant women, and microvesicular fraction of the brush border membrane of human placental syncytiotrophoblast at 23 + 2 C were studied. Interaction of nCBG in complex with a steroid with each of the two types for specific binding was found associated with transmcmbranous transfer of glycoprotein. Interaction of rCBG with binding sites of both types did not involve subsequent glycoprotein transfer through the membrane. Possibility of penetration of only one CBG variant through syncytiotrophoblast membrane suggests the presence of different mechanisms of these glycoproteins' participation in the hormonal effects of steroids associated with them.

Specific binding of lactoferrin to brush-border membrane: ontogeny and effect of glycan chain

1988 ◽  
Vol 254 (4) ◽  
pp. G580-G585 ◽  
Author(s):  
L. A. Davidson ◽  
B. Lonnerdal
Keyword(s):  
Human Milk ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Specific Binding ◽  
Carbohydrate Chain ◽  
Membrane Vesicles ◽  
Iron Bioavailability ◽  
Bovine Lactoferrin ◽  
Binding Studies ◽  
Intestinal Brush Border Membrane

Bioavailability of iron from human milk is exceptionally high. It has been suggested that lactoferrin, the major iron-binding protein in human milk, may participate in this high iron bioavailability from milk. We examined the interaction of lactoferrin with the intestinal brush-border membrane using the rhesus monkey as a model. Brush-border membrane vesicles were prepared from monkeys of various ages. Binding studies with 59Fe-labeled human and monkey lactoferrin were performed to examine interaction of lactoferrin with the brush-border membrane. Specific saturable binding of lactoferrin was found at all ages studied (fetal, suckling infant, weaned infant, juvenile, and adult). The dissociation constant for lactoferrin-receptor binding was 9 X 10(-6) M. In contrast, no binding of serum transferrin or bovine lactoferrin occurred. Removal of fucose from the lactoferrin glycans resulted in a significant decrease in binding. It was concluded that lactoferrin in milk may function in the process of iron absorption through interaction with a small intestinal receptor and that fucosylated glycans on the carbohydrate chain of lactoferrin are necessary for receptor recognition.

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