The effect of sunlight on the protein crystals from Bacillus thuringiensis var. kurstaki HD1 and NRD12: A Raman spectroscopic study

Pozsgay, Marianne; Fast, Paul G.; Kaplan, Harvey; Carey, Paul R.

doi:10.1016/0022-2011(87)90089-9

Cited by 75 publications

(45 citation statements)

References 9 publications

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“…One major problem of field applications of Cry toxins is that their exposure to sunlight (20) can bring about reduced bioactivity. It has been demonstrated that chromophores are the prime light-absorbing agents.…”

Section: Discussionmentioning

confidence: 99%

Role of Tryptophan Residues in Toxicity of Cry1Ab Toxin from Bacillus thuringiensis

Padilla

Pardo-López

Riva

et al. 2006

Appl Environ Microbiol

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Bacillus thuringiensis produces insecticidal proteins (Cry protoxins) during the sporulation phase as parasporal crystals. During intoxication, the Cry protoxins must change from insoluble crystals into membraneinserted toxins which form ionic pores. The structural changes of Cry toxins during oligomerization and insertion into the membrane are still unknown. The Cry1Ab toxin has nine tryptophan residues; seven are located in domain I, the pore-forming domain, and two are located in domain II, which is involved in receptor recognition. Eight Trp residues are highly conserved within the whole family of three-domain Cry proteins, suggesting an essential role for these residues in the structural folding and function of the toxin. In this work, we analyzed the role of Trp residues in the structure and function of Cry1Ab toxin. We replaced the Trp residues with phenylalanine or cysteine using site-directed mutagenesis. Our results show that W65 and W316 are important for insecticidal activity of the toxin since their replacement by Phe reduced the toxicity against Manduca sexta. The presence of hydrophobic residue is important at positions 117, 219, 226, and 455 since replacement by Cys affected either the crystal formation or the insecticidal activity of the toxin in contrast to replacement by Phe in these positions. Additionally, some mutants in positions 219, 316, and 455 were also affected in binding to brush border membrane vesicles (BBMV). This is the first report that studies the role of Trp residues in the activity of Cry toxins.

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Section: Discussionmentioning

confidence: 99%

Role of Tryptophan Residues in Toxicity of Cry1Ab Toxin from Bacillus thuringiensis

Padilla

Pardo-López

Riva

et al. 2006

Appl Environ Microbiol

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“…Site-directed mutagenesis and chemical modification will then be used to manipulate these determinants to achieve maximum benefit for forestry applications. In addition, a mechanism of sunlight inactivation of the crystal protein has been established (Pozsgay et al 1987) and ways of improving stability in sunlight are being explored. Achievements to date will accelerate the development of novel, targetspecific microbial insecticides based on recombinant Bt.…”

Section: Strain Selection and Modificationmentioning

confidence: 99%

Development and Current Status of Bacillus thuringiensis for Control of Defoliating Forest Insects

Frankenhuyzen¹

1990

The Forestry Chronicle

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RCsumCBacillus thuringiensis (Bt) is a naturally occurring bacterium Bacillus thuringiensis (B. t.) est une bactkrie naturelle, aujourthat is now widely used for control of spruce budworm and d'hui largement utilisCe contre la tordeuse des bourgeons de several other defoliating forest insects in Canada. It took more 1'Cpinette et plusieurs autres dCfoliateurs des forCts du Canada. than 25 years of research and development to bring Bt from first Depuis son premier emploi expCrimental, au dCbut des annCes experimental use in the early 1960s into full operational use in 60, jusqu'a son utilisation en grand, dans le milieu des anntes the mid 1980s. Critical to this process was the adoption of HD-1 80, il s'est pass6 plus de 25 annCes de recherche-dCveloppement. for commercial use, the standardization of formulations based Une Ctape critique de cette Cvolution a Ct C l'adoption du HD-1 on international units, and the development of higher potency pour emploi industriel, la normalisation des prCparations grice products. An increase in product potency from 4 BIUIL in the B l'emploi des unitCs internationales ainsi que la mise au point early 1970s to 16.9 BIUIL in the mid 1980s, concomittant with de produits plus puissants. Ainsi, l'accroissement de la puisimprovements in formulation and application technology, sance, de 4 unitCs biologiques internationales au litre (UBIIL), reduced treatment costs while at the same time improving reliaau dCbut des annCes 70, B 16,9, au milieu des annCes 80, en bility of efficacy. A shift in political climate pushed Bt into operam&me temps que les amCliorations des techniques de prCparational use by 1985. Since then, Bt has been used in more than tion et d'application, ont permis de rtduire les coOts du traitehalf of all spruce budworm control programs. The use of highment tout en amCliorant la fiabilitC de l'efficacitk. Un nouveau potency formulations (12.7 to 16.9 BIUIL) applied undiluted climat politique a favoris6 l'emploi en grand de B.t. dks 1985. at 30 BIU in 2.4 Llha or less has significantly reduced but not Depuis, B.t. a servi dans plus de la moitiC de tous les eliminated initial constraints of high treatment costs and inconprogrammes antitordeuse. Le recours B des prkparations trks sistent efficacy. Current research is focussed on further reducing puissantes (de 12,7 B 16,9 UBIIL) appliquCes sans dilution B these constraints. In the short term, registration of formulations raison de 2,4 Llha a permis de rCduire considCrablement, sans containing 25 BIUIL or more is expected to permit application les Climiner complktement, les contraintes initiales posies par of reduced dosages in less than 1 Llha and to clear the way for les coDts ClevCs du traitement et I'efficacitC inconsta~te. La adoption of a split application scheme to increase reliability of recherche actuelle se propose de rMuire ces contraintes. A court efficacy. Selection and commercialization of more effective terme, I'homologation des prkparations renfermant 25 UBIIL strains and the enhancement of natural s...

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“…In present study, decisions on when to treat pest infestations were based on field scouting, rather than fixed thresholds (Table 1). Timing of Bt spray applications is a crucial factor (Ghidiu and Zehnder, 1993) because of differential toxicity against various life stages (Ferro and Lyon, 1991), feeding time preferences of certain insect larvae like H. armigera (Karim et al, 1999a), UV sensitivity of Insecticidal Crystal Proteins (Pozsgay et al, 1987) and other multiple environmental factors (Leong et al, 1980). It is evident from Table 3 that all Bt formulations were toxic to the larvae of Helicoverpa armigera and Earias vitella, but CAMB Bt formulation proved to be the most effective followed by the commercial grade formulations at all the concentrations used in present study.…”

Section: Resultsmentioning

confidence: 99%

Field Efficacy of CAMB Bacillus thuringiensis Biopesticide to Control Helicoverpa armigera (Hübner) and Earias vitella (Fabricius) in Okra Crop

Karim¹,

Zafar²,

Nasir³

et al. 2000

Pakistan J. of Biological Sciences

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CAMB Bacillus thuringiensis formulation and two other commercial Bt formulations (Agree and Larvo Bt) were tested on Okra fields to control two lepidopteran pests, Helicoverpa armigera and Earias vitella. CAMB Bt formulation was tested from 250-g/h dose to 1500 g/h dose to see the efficacy against target insect pests. Commercial Bt formulations, Agree and Larvo Bt were used as standard with one dose of 1000 g/h. All microbial insecticides successfully controlled H. armigera and E. vitella larvae in okra field. The efficacy of locally developed Bt formulation was promising in comparison to Agree and Larvo BT.

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The effect of sunlight on the protein crystals from Bacillus thuringiensis var. kurstaki HD1 and NRD12: A Raman spectroscopic study

Cited by 75 publications

References 9 publications

Role of Tryptophan Residues in Toxicity of Cry1Ab Toxin from Bacillus thuringiensis

Role of Tryptophan Residues in Toxicity of Cry1Ab Toxin from Bacillus thuringiensis

Development and Current Status of Bacillus thuringiensis for Control of Defoliating Forest Insects

Field Efficacy of CAMB Bacillus thuringiensis Biopesticide to Control Helicoverpa armigera (Hübner) and Earias vitella (Fabricius) in Okra Crop

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