Ion Channel Activity of N-Terminal Fragments from CryIA(c) Delta-Endotoxin

Walters, Frederick S.; Slatin, Stephen L.; Kulesza, Caroline; English, Leigh

doi:10.1006/bbrc.1993.2337

Cited by 62 publications

(39 citation statements)

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“…We repeated these experiments and never saw channel activity (n = 25) unless > 5 pM toxin was used. The single channel transitions observed with pM concentrations of toxin were cationic and similar to those described earlier [10][11][12][13].…”

Section: Toxin Responses Of Planar Lipid Bilayers Containing Bbmvsupporting

confidence: 63%

“…It has been shown that the purified toxins alone can induce single channel activity in PLB [10][11][12][13]. We repeated these experiments and never saw channel activity (n = 25) unless > 5 pM toxin was used.…”

Section: Toxin Responses Of Planar Lipid Bilayers Containing Bbmvmentioning

confidence: 99%

“…In the absence of specific receptors CrylA(c), CryIIIA, CrylIIB2 and CrylC toxins form cation-selective channels at alkaline pH; CrylC also forms anion-selective channels at pH 6.0, in planar bilayers [10][11][12][13]. *Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

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δ‐Endotoxins induce cation channels in Spodoptera frugiperda brush border membranes in suspension and in planar lipid bilayers

et al. 1995

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Section: Toxin Responses Of Planar Lipid Bilayers Containing Bbmvsupporting

confidence: 63%

Section: Toxin Responses Of Planar Lipid Bilayers Containing Bbmvmentioning

confidence: 99%

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δ‐Endotoxins induce cation channels in Spodoptera frugiperda brush border membranes in suspension and in planar lipid bilayers

et al. 1995

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“…Domain I consists of a bundle of seven (Cry3A) or eight (Cry1Aa) ␣-helices. By site-directed mutagenesis or hybrid toxins, it was shown that domain I inserts itself into the epithelial membranes of the larvae of the sensitive insects and forms pores in them (3,17,43,46). Domain II, which contains three antiparallel ␤-sheets in both the Cry3A and Cry1Aa toxins and two additional short ␣-helices in Cry1Aa, was suggested to be the domain that binds to the epithelial membrane receptors of the sensitive larvae and the determinant of the specificities of the toxins (20,22,28,41).…”

Section: Discussionmentioning

confidence: 99%

Cloning and analysis of the first cry gene from Bacillus popilliae

et al. 1997

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An 80-kDa parasporal crystal protein was detected in protein extracts of sporangia of Bacillus popilliae isolated from a diseased larva of the common cockchafer (Melolontha melolontha L.). Amino acid analysis of tryptic peptides revealed significant homology to the Cry2Aa endotoxins of Bacillus thuringiensis. The gene cryBP1 (cry18Aa1), which codes for the parasporal crystal protein, was found in a putative cry operon on the bacterial chromosome, which contains at least one further (smaller) open reading frame, orf1. The 706-aminoacid-long CryBP1 (Cry18Aa1) protein has a predicted molecular mass of 79 kDa and shows about 40% sequence identity to the Cry2 polypeptides of B. thuringiensis. In the light of published observations which suggest that the parasporal crystal proteins of B. popilliae are slightly toxic to their grub hosts, we propose the following survival strategy of B. popilliae. As an obligate pathogen of grubs, B. popilliae germinates in the gut of a grub and the parasporal crystal proteins are released and activated. The activated protein does not cause colloid osmotic lysis but instead damages the gut wall somehow to allow the vegetative cells to enter the hemolymph more easily. By becoming a parasite, B. popilliae can continue to proliferate efficiently while the living grub provides a food supply. This process is in contrast to that of B. thuringiensis, which rapidly kills the insect and is then limited to growth on the larval carcass.The gram-positive, spore-forming bacterium Bacillus popilliae Dutky (14) is the obligate causal agent of milky disease of scarab larvae. The name of the disease comes from the milkywhite appearance of the normally clear hemolymph, which is due to the extremely high number of spores generated in the hemolymph (2 ϫ 10 9 to 5 ϫ 10 9 spores per larva) during the infection of the grubs by B. popilliae (21; for reviews, see references 7, 26, and 37). B. popilliae preparations have been used for more than 50 years in the United States for suppression of Japanese beetle larvae (Popillia japonica Newman) (for a review, see reference 25). In fact, this bacterium was the first microorganism registered in that country as an insecticide.For biological control of grubs, only B. popilliae spore preparations can be used, since vegetative cells rapidly lose viability in the soil. Despite considerable research aimed at achieving efficient in vitro production of spores, only very low levels have ever been attained in the laboratory. The lack of methods to efficiently induce sporulation in vitro has been the major factor preventing more research and development projects for these bacteria (38).During sporulation, B. popilliae forms parasporal crystals in a manner reminiscent of Bacillus thuringiensis, which is wellknown as a specific microbial pesticide for larvae of varieties of Lepidoptera, Diptera, and Coleoptera (23). However, the role of the parasporal crystals in B. popilliae pathology remains unclear. Weiner isolated parasporal bodies from B. popilliae NRRL 2309S, a pathogen of ...

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“…In these Cry proteins, domain I consists of seven alpha helices in which helix 5 is surrounded by the others, forming a helical bundle. Several studies have shown that this domain is responsible for channel ion formation (Walters et al 1993, von Tersch et al 1994. Domain II consists of three antiparallel ß-sheets joined in a greek key topology, arranged in a ß-prism, and its function is associated with receptor recognition and binding (Schnepf et al 1990, Gill et al 1992, Knowles 1994, Lu et al 1994.…”

mentioning

confidence: 99%