- Article -
| In Silico Biology 7, 0029 (2007); ©2007, Bioinformation Systems e.V. |
In silico analysis of voltage-gated sodium channel in relation to DDT resistance in vector mosquitoes
Rengaraj Rajesh1, Kasinathan Gunasekaran2*, Subramanian Muthukumaravel2, Kothandapani Balaraman2 and Purusothaman Jambulingam2
1 School of Chemical and Biotechnology, SASTRA University, Thanjavur - 613 402, India
2 Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry - 605 006, India
* Corresponding author
Email: k_guna@yahoo.com
Edited by E. Wingender; received December 20, 2006; revised April 04, 2007; accepted April 05, 2007; published April 22, 2007
Abstract
The voltage-gated sodium channel (VGSC) is the target site for insecticides such as DDT and synthetic pyrethroids. A single base (A-T) change in the knock-down resistance (kdr) allele leads to an amino acid substitution at position 267 that confers the target-mediated resistance to DDT and synthetic pyrethroids in Anopheles gambiae. A theoretical model of the VGSC domain II that contains the site of mutation was constructed using the K+ channel protein of Aeropyrum pernix as a template. The validated model with 88.6% residues in the favored region was subjected to the CASTp program that predicted 30 pockets in the modeled domain II for ligand interaction. In the model, at position 267, leucine was manually replaced with phenylalanine. When this altered model was subjected to the CASTp program, the search results showed the same number of pockets. The docking results indicate that DDT interacts with the modeled VGSC domain II at position 275 in the presence of leucine or in the presence of phenylalanine (binding energy = −5.32 kcal/mol, −6.21 kcal/mol). It appears from the results that the mutation at position 267 has no direct influence on the interaction of DDT with the target protein. Therefore, to understand the interaction affinity of DDT with the target and influence of the mutation on the existence of active sites / pockets in relation to ligand binding, a whole VGSC model is necessary.
Keywords: DDT, target mediated resistance, kdr, 3D model, VGSC domain-II, Anopheles gambiae, ligand interaction pockets, CASTp