In silico Structural Prediction of E6 and E7 Proteins of Human Papillomavirus Strains by Comparative Modeling

More than 200 different types of Human papillomavirus (HPV) are identified, 40 transmit extensively through sexual contacts affecting the genital tract. HPV strains have been etiologically linked to vaginal, vulvar, penile, anal, oral and cervical cancer (99.7%) as a result of mutations leading to cell transformations due to interference of E6 and E7 oncoproteins with p53 and pRB tumor suppressor genes respectively, besides other cellular proteins. As structures of E6 and E7 proteins are not available, the simultaneous structural analysis of E6 and E7 proteins of 50 different HPV strains was carried out in detail for prediction and validation, using bioinformatics tools. E6 and E7 proteins sequences were retrieved in FASTA format from NCBI and their structures predicted by comparative modeling using modeller9v6 software. Further, most of the HPV strains showed good stereochemistry results in most favored regions when subjected to PROCHECK analysis and subsequently each protein was validated using ProSA-web tool. The work carried out on comparing and exploring the structural variations in these oncogenic proteins might help in genome based drugs and vaccines designing, beyond their limitations.