Bacillus thuringiensis Cry4A and Cry4B Mosquito-larvicidal Proteins: Homology-based 3D Model and Implications for Toxin Activity
| Autor: | Somphob Leetachewa, Teerakiat Kerdcharoen, Sakol Panyim, Panapat Uawithya, Chanan Angsuthanasombat, Walairat Pornwiroon, Puey Ounjai, Gerd Katzenmeier |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Circular dichroism Molecular model Bacterial Toxins Molecular Sequence Data 3d model Crystal structure Biochemistry Protein Structure Secondary Homology (biology) Hemolysin Proteins Bacterial Proteins Aedes Bacillus thuringiensis Animals Amino Acid Sequence Homology modeling Molecular Biology Bacillus thuringiensis Toxins biology Reproducibility of Results General Medicine biology.organism_classification Protein Structure Tertiary Endotoxins Larva Sequence Alignment Delta endotoxin |
| Zdroj: | BMB Reports. 37:304-313 |
| ISSN: | 1976-6696 |
| DOI: | 10.5483/bmbrep.2004.37.3.304 |
| Popis: | Three-dimensional (3D) models for the 65-kDa activated Cry4A and Cry4B delta-endotoxins from Bacillus thuringiensis subsp. israelensis that are specifically toxic to mosquito-larvae were constructed by homology modeling, based on atomic coordinates of the Cry1Aa and Cry3Aa crystal structures. They were structurally similar to the known structures, both derived 3D models displayed a three-domain organization: the N-terminal domain (I) is a seven-helix bundle, while the middle and C-terminal domains are primarily comprise of anti-parallel beta-sheets. Circular dichroism spectroscopy confirmed the secondary structural contents of the two homology-based Cry4 structures. A structural analysis of both Cry4 models revealed the following: (a) Residues Arg-235 and Arg-203 are located in the interhelical 5/6 loop within the domain I of Cry4A and Cry4B, respectively. Both are solvent exposed. This suggests that they are susceptible to tryptic cleavage. (b) The unique disulphide bond, together with a proline-rich region within the long loop connecting alpha4 and alpha5 of Cry4A, were identified. This implies their functional significance for membrane insertion. (c) Significant structural differences between both models were found within domain II that may reflect their different activity spectra. Structural insights from this molecular modeling study would therefore increase our understanding of the mechanic aspects of these two closely related mosquito-larvicidal proteins. |
| Databáze: | OpenAIRE |
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