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Diversity of protein inclusion bodies and identification of mosquitocidal protein in Bacillus thuringiensis subsp.
Abstract:
Bacillus thuringiensis subsp. israelensis produces, during sporulation, protein inclusion bodies of wide ranging sizes, all of which are toxic to mosquitoes. Two proteins are present in the smallest protein bodies (less than 0.2 micron dia.), but the number of proteins increases with increasing size of protein bodies. The largest bodies (greater than 1.5 micron dia.) contain seven proteins. All of the proteins are synthesized at different times during sporulation and are added to developing protein bodies in a stepwise manner. The protein component responsible for mosquitocidal activity is a 65,000-dalton protein, that is present in all of the protein bodies.
Insights
Bacillus thuringiensis israelensis produces mosquito-toxic protein crystals during sporulation. A key 65,000-dalton protein is present in all crystal sizes, driving mosquitocidal activity.
Area of Science:
- Microbiology
- Molecular Biology
- Insect Toxicology
Background:
- Bacillus thuringiensis subsp. israelensis (Bti) is a bacterium known for producing insecticidal toxins.
- During its life cycle, Bti forms protein inclusion bodies (crystals) that exhibit toxicity to specific insect larvae, notably mosquitoes.
- The composition and structure of these Bti crystals vary, influencing their efficacy and spectrum of activity.
Purpose of the Study:
- To investigate the composition of protein inclusion bodies produced by Bacillus thuringiensis subsp. israelensis.
- To identify the specific protein(s) responsible for the mosquitocidal activity of these inclusion bodies.
- To understand the temporal synthesis and assembly of these proteins during bacterial sporulation.
Main Methods:
- Analysis of protein inclusion bodies of varying sizes produced by Bti during sporulation.
- Characterization of protein content within different size fractions of inclusion bodies.
- Determination of the molecular weight and presence of specific proteins across the inclusion body size spectrum.
Main Results:
- Bti produces protein inclusion bodies ranging in size, all possessing mosquitocidal properties.
- Smaller inclusion bodies (<0.2 micron) contain two proteins, while larger ones (>1.5 micron) contain up to seven.
- A 65,000-dalton protein, synthesized stepwise during sporulation, is present in all inclusion bodies and is responsible for mosquitocidal activity.
Conclusions:
- The mosquitocidal activity of Bti is attributed to a specific 65,000-dalton protein present in all inclusion bodies.
- The stepwise synthesis and assembly of multiple proteins into inclusion bodies of increasing size suggest a complex developmental process.
- Understanding the Bti crystal composition provides insights into targeted mosquito control strategies.