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 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 Common, but Complex, Mode of Resistance of Plutella xylostella to Bacillus thuringiensis Toxins Cry1Ab and Cry1Ac

2005 ◽  
Vol 71 (11) ◽  
pp. 6863-6869 ◽  
Author(s):  
Ali H. Sayyed ◽  
Roxani Gatsi ◽  
M. Sales Ibiza-Palacios ◽  
Baltasar Escriche ◽  
Denis J. Wright ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Resistance Genes ◽  
Plutella Xylostella ◽  
Specific Binding ◽  
Management Strategies ◽  
Cross Resistance ◽  
Single Pair ◽  
Dominant Trait ◽  
Binding Studies ◽  
Susceptible Population

ABSTRACT A field collected population of Plutella xylostella (SERD4) was selected in the laboratory with Bacillus thuringiensis endotoxins Cry1Ac (Cry1Ac-SEL) and Cry1Ab (Cry1Ab-SEL). Both subpopulations showed similar phenotypes: high resistance to the Cry1A toxins and little cross-resistance to Cry1Ca or Cry1D. A previous analysis of the Cry1Ac-SEL showed incompletely dominant resistance to Cry1Ac with more than one factor, at least one of which was sex influenced. In the present study reciprocal mass crosses between Cry1Ab-SEL and a laboratory susceptible population (ROTH) provided evidence that Cry1Ab resistance was also inherited as incompletely dominant trait with more than one factor, and at least one of the factors was sex influenced. Analysis of single pair mating indicated that Cry1Ab-SEL was still heterogeneous for Cry1Ab resistance genes, showing genes with different degrees of dominance. Binding studies showed a large reduction of specific binding of Cry1Ab and Cry1Ac to midgut membrane vesicles of the Cry1Ab-SEL subpopulation. Cry1Ab-SEL was found to be more susceptible to trypsin-activated Cry1Ab toxin than protoxin, although no defect in toxin activation was found. Present and previous results indicate a common basis of resistance to both Cry1Ab and Cry1Ac in selected subpopulations and suggest that a similar set of resistance genes are responsible for resistance to Cry1Ab and Cry1Ac and are selected whichever toxin was used. The possibility of an incompletely dominant trait of resistant to these toxins should be taken into account when considering refuge resistance management strategies.

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.

scholarly journals Cadherin Fragments from Anopheles gambiae Synergize Bacillus thuringiensis Cry4Ba's Toxicity against Aedes aegypti Larvae

2009 ◽  
Vol 75 (22) ◽  
pp. 7280-7282 ◽  
Author(s):  
Youngjin Park ◽  
Gang Hua ◽  
Mohd Amir F. Abdullah ◽  
Khalidur Rahman ◽  
Michael J. Adang
Keyword(s):  
Bacillus Thuringiensis ◽  
Aedes Aegypti ◽  
Anopheles Gambiae ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Diabrotica Virgifera Virgifera ◽  
Extracellular Domain ◽  
Diabrotica Virgifera ◽  
Appl Environ ◽  
High Affinity

ABSTRACT A peptide from cadherin AgCad1 of Anopheles gambiae larvae was reported as a synergist of Bacillus thuringiensis subsp. israelensis Cry4Ba's toxicity to the Anopheles mosquito (G. Hua, R. Zhang, M. A. Abdullah, and M. J. Adang, Biochemistry 47:5101-5110, 2008). We report that CR11 to the membrane proximal extracellular domain (MPED) (CR11-MPED) and a longer peptide, CR9 to CR11 (CR9-11), from AgCad1 act as synergists of Cry4Ba's toxicity to Aedes aegypti larvae, but a Diabrotica virgifera virgifera cadherin-based synergist of Cry3 (Y. Park, M. A. F. Abdullah, M. D. Taylor, K. Rahman, and M. J. Adang, Appl. Environ. Microbiol. 75:3086-3092, 2009) did not affect Cry4Ba's toxicity. Peptides CR9-11 and CR11-MPED bound Cry4Ba with high affinity (13 nM and 23 nM, respectively) and inhibited Cry4Ba binding to the larval A. aegypti brush border membrane. The longer CR9-11 fragment was more potent than CR11-MPED in enhancing Cry4Ba against A. aegypti.

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.

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.

Plasminogen-Plasmin System IX. Specific Binding of Tranexamic Acid to Plasmin

1975 ◽  
Vol 33 (03) ◽  
pp. 573-585 ◽  
Author(s):  
Masahiro Iwamoto
Keyword(s):  
Tranexamic Acid ◽  
Affinity Chromatography ◽  
Dissociation Constant ◽  
Factor Xiii ◽  
Specific Binding ◽  
The Other ◽  
Inhibitory Mechanism ◽  
Binding Studies ◽  
Similar Affinity ◽  
Fibrin Structure

SummaryInteractions between tranexamic acid and protein were studied in respect of the antifibrinolytic actions of tranexamic acid. Tranexamic acid did neither show any interaction with fibrinogen or fibrin, nor was incorporated into cross-linked fibrin structure by the action of factor XIII. On the other hand, tranexamic acid bound to human plasmin with a dissociation constant of 3.5 × 10−5 M, which was very close to the inhibition constant (3.6 × 10−5 M) for this compound in inhibiting plasmin-induced fibrinolysis. The binding site of tranexamic acid on plasmin was not the catalytic site of plasmin, because TLCK-blocked plasmin also showed a similar affinity to tranexamic acid (the dissociation constant, 2.9–4.8 × 10−5 M).In the binding studies with the highly purified plasminogen and TLCK-plasmin preparations which were obtained by affinity chromatography on lysine-substituted Sepharose, the molar binding ratio was shown to be 1.5–1.6 moles tranexamic acid per one mole protein.On the basis of these and other findings, a model for the inhibitory mechanism of tranexamic acid is presented.

Studies of the Mechanism for Enhanced Cell Surface Factor VIIa/Tissue Factor Activation of Factor X on Fibroblast Monolayers after Their Exposure to N-Ethylmaleimide

1994 ◽  
Vol 72 (06) ◽  
pp. 848-855 ◽  
Author(s):  
Dzung The Le ◽  
Samuel I Rapaport ◽  
L Vijaya Mohan Rao
Keyword(s):  
Cell Surface ◽  
Tissue Factor ◽  
Factor Viia ◽  
Cell Damage ◽  
Specific Binding ◽  
Surface Membrane ◽  
Annexin V ◽  
Factor X ◽  
Binding Studies ◽  
Anionic Phospholipid

SummaryFibroblast monolayers constitutively expressing surface membrane tissue factor (TF) were treated with 0.1 mM N-ethylmaleimide (NEM) for 1 min to inhibit aminophospholipid translocase activity without inducing general cell damage. This resulted in increased anionic phospholipid in the outer leaflet of the cell surface membrane as measured by the binding of 125I-annexin V and by the ability of the monolayers to support the generation of prothrombinase. Specific binding of 125I-rVIIa to TF on NEM-treated monolayers was increased 3- to 4-fold over control monolayers after only brief exposure to 125I-rVIIa, but this difference progressively diminished with longer exposure times. A brief exposure of NEM-treated monolayers to rVIIa led to a maximum 3- to 4-fold enhancement of VIIa/TF catalytic activity towards factor X over control monolayers, but, in contrast to the binding studies, this 3- to 4-fold difference persisted despite increasing time of exposure to rVIIa. Adding prothrombin fragment 1 failed to diminish the enhanced VIIa/TF activation of factor X of NEM-treated monolayers. Moreover, adding annexin V, which was shown to abolish the ability of NEM to enhance factor X binding to the fibroblast monolayers, also failed to diminish the enhanced VIIa/TF activation of factor X. These data provide new evidence for a possible mechanism by which availability of anionic phospholipid in the outer layer of the cell membrane limits formation of functional VIIa/TF complexes on cell surfaces.

Sign in / Sign up

Export Citation Format

Share Document