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A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

Chen W, Liu C, Xiao Y, Zhang D, Zhang Y, Li X, Tabashnik BE, Wu K - PLoS ONE (2015)

Bottom Line: Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains.Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase.The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

View Article: PubMed Central - PubMed

Affiliation: The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing, 100193, China.

ABSTRACT
Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

No MeSH data available.


Related in: MedlinePlus

The affinities of binding of Cry1Ac to HaALP1f.Experimental curves (jagged line) are shown overlaid with fitted curves (smooth line) obtained with the 1:1 Langmuir binding model. The overlaid BIAcore response curves are shown for HaALP1f injections at 31.25, 62.5, 125, 250, and 500 nM.
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pone.0126288.g006: The affinities of binding of Cry1Ac to HaALP1f.Experimental curves (jagged line) are shown overlaid with fitted curves (smooth line) obtained with the 1:1 Langmuir binding model. The overlaid BIAcore response curves are shown for HaALP1f injections at 31.25, 62.5, 125, 250, and 500 nM.

Mentions: Ligand blot analysis revealed that the lysates of E. coli cells expressed with his-tagged HaALP1f had a protein of the same size with the his-tagged HaALP1f (35–37 kDa) that bound to the activated Cry1Ac (lane 2 in Fig 5). And the intensity of the Cry1Ac-binding protein band was much stronger in the Ni column-purified proteins from IPTG-induced ALP-expressing E. coli cells (lane 3 in Fig 5) than in the crude lysates of E. coli cells expressed with his-tagged HaALP1f. By contrast, the lysates of control E. coli cells transformed with the empty pET28a+ vector did not have a protein capable of binding to the activated Cry1Ac (Lane 1 in Fig 5). In addition, overlay plot of the surface plasmon resonance (SPR) sensorgrams between different concentrations of the purified HaALP1f and immobilized activated Cry1Ac also showed HaALP1f-activated Cry1Ac binding interaction (Fig 6). A 1:1 binding stoichiometry produced the following apparent rate constants of the bimolecular interaction: ka = 3.27× 105 M-1s-1 and kd = 2.48 × 10-3 s-1, KD = 7.58 nM.


A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

Chen W, Liu C, Xiao Y, Zhang D, Zhang Y, Li X, Tabashnik BE, Wu K - PLoS ONE (2015)

The affinities of binding of Cry1Ac to HaALP1f.Experimental curves (jagged line) are shown overlaid with fitted curves (smooth line) obtained with the 1:1 Langmuir binding model. The overlaid BIAcore response curves are shown for HaALP1f injections at 31.25, 62.5, 125, 250, and 500 nM.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4401514&req=5

pone.0126288.g006: The affinities of binding of Cry1Ac to HaALP1f.Experimental curves (jagged line) are shown overlaid with fitted curves (smooth line) obtained with the 1:1 Langmuir binding model. The overlaid BIAcore response curves are shown for HaALP1f injections at 31.25, 62.5, 125, 250, and 500 nM.
Mentions: Ligand blot analysis revealed that the lysates of E. coli cells expressed with his-tagged HaALP1f had a protein of the same size with the his-tagged HaALP1f (35–37 kDa) that bound to the activated Cry1Ac (lane 2 in Fig 5). And the intensity of the Cry1Ac-binding protein band was much stronger in the Ni column-purified proteins from IPTG-induced ALP-expressing E. coli cells (lane 3 in Fig 5) than in the crude lysates of E. coli cells expressed with his-tagged HaALP1f. By contrast, the lysates of control E. coli cells transformed with the empty pET28a+ vector did not have a protein capable of binding to the activated Cry1Ac (Lane 1 in Fig 5). In addition, overlay plot of the surface plasmon resonance (SPR) sensorgrams between different concentrations of the purified HaALP1f and immobilized activated Cry1Ac also showed HaALP1f-activated Cry1Ac binding interaction (Fig 6). A 1:1 binding stoichiometry produced the following apparent rate constants of the bimolecular interaction: ka = 3.27× 105 M-1s-1 and kd = 2.48 × 10-3 s-1, KD = 7.58 nM.

Bottom Line: Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains.Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase.The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

View Article: PubMed Central - PubMed

Affiliation: The State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing, 100193, China.

ABSTRACT
Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

No MeSH data available.


Related in: MedlinePlus