Related Experiment Videos
Proteolytic processing of the mosquitocidal toxin from Bacillus sphaericus SSII-1
T Thanabalu1, J Hindley, C Berry
1Insecticidal Toxins Laboratory, National University of Singapore.
Journal of Bacteriology
|August 1, 1992
Summary
The mosquitocidal protein Mtx21 from Bacillus sphaericus is toxic to Culex quinquefasciatus larvae. Proteolytic cleavage reveals a 27-kDa peptide homologous to ADP-ribosyltransferase toxins.
Area of Science:
- Molecular Biology
- Biochemistry
- Toxicology
Background:
- Bacillus sphaericus produces mosquitocidal toxins.
- The mosquitocidal toxin (Mtx) protein is a precursor to active toxins.
Purpose of the Study:
- To characterize the Mtx21 protein derived from Mtx.
- To determine the toxicity and cleavage products of Mtx21.
Main Methods:
- Expression and purification of Mtx21 as a glutathione S-transferase fusion protein in E. coli.
- Thrombin cleavage to release Mtx21.
- Toxicity assays on Culex quinquefasciatus larvae.
- Proteolytic digestion with gut extracts and trypsin.
- N-terminal sequencing of cleavage peptides.
Main Results:
- Mtx21 is toxic to Culex quinquefasciatus larvae with an LC50 of 15 ng/ml.
- Proteolytic cleavage by gut extracts and trypsin yielded 70-kDa and 27-kDa peptides.
- The 27-kDa peptide contains homology to ADP-ribosyltransferase toxin catalytic domains.
- The 70-kDa peptide contains three internal homology regions.
Conclusions:
- Mtx21 is an active mosquitocidal protein.
- The 27-kDa fragment is likely responsible for the ADP-ribosyltransferase-like activity.
- Further characterization of the 70-kDa peptide is warranted.