Bacillus thuringiensis HD-73 spores have surface-localized Cry1Ac toxin: Physiological and pathogenic consequences

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Abstract

Spores from Cry+ strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry- strains of B. thuringiensis did not. The Cry+ spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry+ spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide- rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.

Original languageEnglish (US)
Pages (from-to)3722-3726
Number of pages5
JournalApplied and environmental microbiology
Volume62
Issue number10
StatePublished - Oct 1 1996

Fingerprint

Bacillus thuringiensis
Spores
toxin
spore
toxins
spores
brush border membrane vesicles
Insects
exine
insect
Germination
Microvilli
vesicle
insects
germination
digestive system
membrane
receptors
Bacillus cereus
Membranes

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

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title = "Bacillus thuringiensis HD-73 spores have surface-localized Cry1Ac toxin: Physiological and pathogenic consequences",
abstract = "Spores from Cry+ strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry- strains of B. thuringiensis did not. The Cry+ spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry+ spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide- rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.",
author = "Cheng Du and Nickerson, {Kenneth W.}",
year = "1996",
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T1 - Bacillus thuringiensis HD-73 spores have surface-localized Cry1Ac toxin

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AU - Du, Cheng

AU - Nickerson, Kenneth W.

PY - 1996/10/1

Y1 - 1996/10/1

N2 - Spores from Cry+ strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry- strains of B. thuringiensis did not. The Cry+ spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry+ spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide- rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.

AB - Spores from Cry+ strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry- strains of B. thuringiensis did not. The Cry+ spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry+ spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide- rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.

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