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A new Cry toxin with a unique two-component dependency from Bacillus sphaericus

Gareth W Jones1, Christina Nielsen-Leroux, Yankun Yang

  • 1Cardiff School of Biosciences, Cardiff University, Museum Ave., Cardiff CF10 3US, UK.

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology
|July 25, 2007
PubMed

Insights

Researchers discovered a novel two-component mosquitocidal toxin, Cry48Aa1/Cry49Aa1, in Bacillus sphaericus strains. This unprecedented toxin combination overcomes existing resistance, offering a new tool for mosquito control.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Insect Toxicology

Background:

  • Bacillus sphaericus produces mosquitocidal Bin proteins, but resistance is a growing concern.
  • Existing resistance necessitates the discovery of novel insecticidal toxins.

Purpose of the Study:

  • To identify and characterize new toxins in Bacillus sphaericus strains resistant to existing mosquitocides.
  • To understand the mechanism of action of novel toxin combinations.

Main Methods:

  • Analysis of resistant Bacillus sphaericus strains.
  • Protein characterization and toxicity assays.
  • Gene family analysis.

Main Results:

  • Discovery of a novel two-component toxin, Cry48Aa1 and Cry49Aa1.
  • Cry48Aa1 is related to Bacillus thuringiensis 3-domain crystal toxins; Cry49Aa1 is related to binary toxins.
  • Toxicity requires both Cry48Aa1 and Cry49Aa1, indicating an unprecedented interaction.
  • High potency of purified Cry48Aa1/Cry49Aa1 against Culex quinquefasciatus larvae.
  • Suboptimal activity in producing bacteria due to low Cry48Aa1 levels.

Conclusions:

  • A new mosquitocidal toxin system, Cry48Aa1/Cry49Aa1, has been identified.
  • This toxin represents a novel combination of gene families, potentially arising from "mix-and-match" evolution.
  • The Cry48Aa1/Cry49Aa1 system offers a promising new avenue for developing mosquito control strategies against resistant populations.

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