Ser-Substituted Mutations of Cys Residues in Bacillus thuringiensis Vip3Aa7 Exert a Negative Effect on its Insecticidal Activity
| Autor: | Shanshan Zhang, Fang Dong, Fangyan Xu, Ziduo Liu, Ruiping Shi, Shuyuan Yi |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Insecticides
Amino Acid Motifs Mutant Bacillus thuringiensis Mutation Missense Sequence alignment Moths Applied Microbiology and Biotechnology Microbiology Serine chemistry.chemical_compound Protein structure Bacterial Proteins medicine Animals Cysteine Cysteine metabolism biology General Medicine biology.organism_classification Trypsin Amino Acid Substitution chemistry Biochemistry Larva Biological Assay medicine.drug |
| Zdroj: | Current Microbiology. 65:583-588 |
| ISSN: | 1432-0991 0343-8651 |
| DOI: | 10.1007/s00284-012-0201-9 |
| Popis: | Vegetative insecticidal proteins (VIPs), which were produced by Bacillus thuringiensis during its vegetative growth stage, display a broad insecticidal spectrum to Lepidoptera larvae. Sequence alignment of the Vip3A-type indicates that three cysteine residues were conserved in Vip3A-type proteins. To determine whether these conserved cysteine residues contributed to the insecticidal activity, the three residues were respectively substituted with serine in the Vip3Aa7 protein by site-directed mutagenesis. Bioassays using the third instar larvae of Plutella xylostella showed that the toxicity of C401S and C507S mutants were completely abolished. To find out the inactivity reason of mutants, three mutants and the wild-type Vip3Aa7 were treated with trypsin. The results indicated that the C507S mutant was rapidly cleaved and resulted in decrease of the 62 kDa toxic core fragment. These results indicated that the replacement of the Cys(507) with a Ser(507) caused decrease in C507S resistance against trypsin degradation. It is suggesting a possible association between insecticidal activity and trypsin sensitivity of Vip3A proteins. This study serves a guideline for the study of Vip3A protein structure and active mechanism. |
| Databáze: | OpenAIRE |
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