Interaction analyses of Bacillus thuringiensis Cry1A toxins with two aminopeptidases from gypsy moth midgut brush border membranes

Valaitis, Algimantas P.

doi:10.1016/s0965-1748(97)00028-3

Cited by 38 publications

(32 citation statements)

References 39 publications

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“…In addition, SBA did not bind to this APN, suggesting that GalNAc moieties were not present in its glycans. It thus appeared that the interaction between Cry1Ac and class 4 APN differed from the interaction of Cry1Ac with class 1 and class 3 APN, where GalNAc was believed to be an important determinant of binding (93,116,177). Cry toxin binding to exogenously expressed class 4 H. virescens APN was also reported (7) and here it was shown by fluorescence microscopy that Cry1Ac could bind to S2 cells expressing APN but not to control cells.…”

Section: Apnsupporting

confidence: 51%

“…Interestingly, ALP expression levels were reduced in a resistant strain of H. virescens, suggesting a functional role in toxicity. The presence of a GPI anchor and the importance of GalNAc in toxin binding shows clear parallels to APN and its interaction with Cry1Ac (93,116,177).…”

Section: Alpmentioning

confidence: 89%

“…By ligand blot analysis, Cry1Ac was shown to bind to purified denatured APN. Binding was also tested by SPR analysis and under these conditions Cry1Ac, but not Cry1Aa or Cry1Ab, bound to native APN and Cry1Ac binding could be completely blocked with competing GalNAc (177). The binding of Cry1Ac to APN was reported to occur in a 1:1 ratio, in contrast to the 2:1 ratio reported for the interaction between Cry1Ac and class 1 M. sexta APN (120) and class 1 H. virescens APN (116).…”

Section: Apnmentioning

confidence: 94%

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Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

Pigott

Ellar

2007

Microbiol Mol Biol Rev

602

598

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SUMMARY Bacillus thuringiensis produces crystalline protein inclusions with insecticidal or nematocidal properties. These crystal (Cry) proteins determine a particular strain's toxicity profile. Transgenic crops expressing one or more recombinant Cry toxins have become agriculturally important. Individual Cry toxins are usually toxic to only a few species within an order, and receptors on midgut epithelial cells have been shown to be critical determinants of Cry specificity. The best characterized of these receptors have been identified for lepidopterans, and two major receptor classes have emerged: the aminopeptidase N (APN) receptors and the cadherin-like receptors. Currently, 38 different APNs have been reported for 12 different lepidopterans. Each APN belongs to one of five groups that have unique structural features and Cry-binding properties. While 17 different APNs have been reported to bind to Cry toxins, only 2 have been shown to mediate toxin susceptibly in vivo. In contrast, several cadherin-like proteins bind to Cry toxins and confer toxin susceptibility in vitro, and disruption of the cadherin gene has been associated with toxin resistance. Nonetheless, only a small subset of the lepidopteran-specific Cry toxins has been shown to interact with cadherin-like proteins. This review analyzes the interactions between Cry toxins and their receptors, focusing on the identification and validation of receptors, the molecular basis for receptor recognition, the role of the receptor in resistant insects, and proposed models to explain the sequence of events at the cell surface by which receptor binding leads to cell death.

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Section: Apnsupporting

confidence: 51%

Section: Alpmentioning

confidence: 89%

Section: Apnmentioning

confidence: 94%

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Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

Pigott

Ellar

2007

Microbiol Mol Biol Rev

602

598

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“…Proteins were eluted in a step gradient of 1 M NaCl in the same buffer. Fractions were analyzed for aminopeptidase activity by a leucine-p-nitroanilide assay described previously (5). APN fractions were probed with biotinylated Cry1Ac and anti-L. dispar APN polyclonal serum using ligand blot overlays as described (5).…”

Section: Methodsmentioning

confidence: 99%

Bivalent Sequential Binding Model of a Bacillus thuringiensis Toxin to Gypsy Moth Aminopeptidase N Receptor

Jenkins¹,

Lee²,

Valaitis³

et al. 2000

Journal of Biological Chemistry

127

143

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Specificity for target insects of Bacillus thuringiensisinsecticidal Cry toxins is largely determined by toxin affinity for insect midgut receptors. The mode of binding for one such toxin-receptor complex was investigated by extensive toxin mutagenesis, followed by realtime receptor binding analysis using an optical biosensor (BIAcore). Wild-type Cry1Ac, a three-domain, lepidopteran-specific toxin, bound purified gypsy moth (Lymantria dispar) aminopeptidase N (APN) biphasically. Site 1 displayed fast association and dissociation kinetics, while site 2 possessed slower kinetics, yet tighter affinity. We empirically determined that two

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“…The majority of Cry1 toxin binding proteins have been identified as aminopeptidases. Aminopeptidase N (APN) has been identified as a binding protein for the Cry1Ac toxin in Manduca sexta, Heliothis virescens, Lymantria dispar, and Plutella xylostella (9,20,33,45). APN has also been identified as a Cry1Aa binding protein in Bombyx mori (18) and as a Cry1C binding protein in M. sexta (32).…”

mentioning

confidence: 99%

Role of Bacillus thuringiensis Cry1 δ Endotoxin Binding in Determining Potency during Lepidopteran Larval Development

Gilliland

Chambers

Bone

et al. 2002

Appl Environ Microbiol

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Five economically important crop pests, Manduca sexta, Pieris brassicae, Mamestra brassicae, Spodoptera exigua, and Agrotis ipsilon, were tested at two stages of larval development for susceptibility to Bacillus thuringiensis toxins Cry1Ac, Cry1Ca, Cry1J, and Cry1Ba. Bioassay results for M. sexta showed that resistance to all four Cry toxins increased from the neonate stage to the third-instar stage; the increase in resistance was most dramatic for Cry1Ac, the potency of which decreased 37-fold. More subtle increases in resistance during larval development were seen in M. brassicae for Cry1Ca and in P. brassicae for Cry1Ac and Cry1J. By contrast, the sensitivity of S. exigua did not change during development. At both larval stages, A. ipsilon was resistant to all four toxins. Because aminopeptidase N (APN) is a putative Cry1 toxin binding protein, APN activity was measured in neonate and third-instar brush border membrane vesicles (BBMV). With the exception of S. exigua, APN activity was found to be significantly lower in neonates than in third-instar larvae and thus inversely correlated with increased resistance during larval development. The binding characteristics of iodinated Cry1 toxins were determined for neonate and third-instar BBMV. In M. sexta, the increased resistance to Cry1Ac and Cry1Ba during larval development was positively correlated with fewer binding sites in third-instar BBMV than in neonate BBMV. The other species-instar-toxin combinations did not reveal positive correlations between potency and binding characteristics. The correlation between binding and potency was inconsistent for the species-instar-toxin combinations used in this study, reaffirming the complex mode of action of Cry1 toxins.The ␦ endotoxins are a family of insecticidal proteins produced by Bacillus thuringiensis during sporulation. These toxins are typically found in parasporal crystals that are released into the environment with the bacterial spores. Numerous ␦ endotoxins produced by B. thuringiensis have been identified and are grouped on the basis of sequence homology and insect specificity (40). The Cry1 toxins are a group of ␦ endotoxins that principally target lepidopteran species, including several important crop pests.The mechanism of action of the Cry1 ␦ endotoxins begins with solubilization of the protoxin in the alkaline larval midgut, followed by proteolytic processing by midgut proteases (40). The stable 60-to 65-kDa toxins then bind to midgut receptors and insert into the apical membrane of brush border epithelial cells to form pores. These pores disrupt functional membrane processes and are ultimately responsible for larval death (40).Each type of Cry1 toxin has a unique spectrum of activity and targets only a small range of lepidopteran species. Within the small target ranges there are dramatic differences in potency between species that are often closely related (12,15,31). Indeed, the potency of a Cry1 toxin can significantly decrease as the larvae age (1, 38). Variations in the potencies of Cry1 toxins ...

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Interaction analyses of Bacillus thuringiensis Cry1A toxins with two aminopeptidases from gypsy moth midgut brush border membranes

Cited by 38 publications

References 39 publications

Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

Role of Receptors in Bacillus thuringiensis Crystal Toxin Activity

Bivalent Sequential Binding Model of a Bacillus thuringiensis Toxin to Gypsy Moth Aminopeptidase N Receptor

Role of Bacillus thuringiensis Cry1 δ Endotoxin Binding in Determining Potency during Lepidopteran Larval Development

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