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Visualization of Bacterial Toxin Induced Responses Using Live Cell Fluorescence Microscopy
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Tightly bound binary toxin in the cell wall of Bacillus sphaericus
Daniela Klein1, Igor Uspensky, Sergei Braun
1Department of Biological Chemistry, A. Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Applied and Environmental Microbiology
|June 29, 2002
Summary
The cell wall of Bacillus sphaericus is a potent mosquito larvicide, acting synergistically with its binary toxin. This toxicity is linked to specific binary toxin proteins (P42 and P51) found within the cell wall.
Area of Science:
- Microbiology
- Insecticide Development
- Molecular Biology
Background:
- Entomopathogenic bacteria, like Bacillus sphaericus, are crucial for biological control of disease vectors.
- Bacillus sphaericus produces a binary toxin, a key component in its larvicidal activity against mosquitoes.
- The exact contribution of bacterial cell wall components to larvicidal activity remains incompletely understood.
Purpose of the Study:
- To investigate the larvicidal activity of Bacillus sphaericus cell walls against Culex pipiens mosquitoes.
- To determine the role of specific binary toxin proteins (P42 and P51) in cell wall toxicity.
- To elucidate the synergistic interaction between cell wall components and binary toxin crystals.
Main Methods:
- Urea extraction of Bacillus sphaericus cell walls.
- Larvicidal assays using Culex pipiens and varying concentrations of cell wall preparations and binary toxin.
- Genetic disruption of the P42 gene in Bacillus sphaericus.
- Co-expression of P42 in Escherichia coli for functional analysis.
Main Results:
- Urea-extracted Bacillus sphaericus cell walls exhibit potent larvicidal activity against Culex pipiens, with LC50 values comparable to the binary toxin.
- Cell wall toxicity develops early in bacterial culture and diminishes with sporulation, preceding peak binary toxin activity.
- Disruption of the P42 gene abolished both cell wall toxicity and crystal formation, indicating P42's essential role.
- Cell wall toxicity is attributed to tightly bound P51 and P42 binary toxin proteins within the cell wall.
- Synergism between cell wall preparations and binary toxin crystals results from suboptimal distribution of binary toxin subunits.
Conclusions:
- Bacillus sphaericus cell walls possess intrinsic larvicidal properties mediated by bound P42 and P51 binary toxin proteins.
- The cell wall serves as an important reservoir for larvicidal proteins, contributing to synergistic effects with binary toxin crystals.
- Understanding these interactions can inform the development of more effective Bacillus sphaericus-based mosquito control strategies.
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