Designing peptides with inhibitory activity on human papillomavirus 16 E1-E2 protein complex formation

Abstract

Human papillomavirus 16 (HPV 16) is a DNA virus that is capable of infecting humans and causing cervical cancer. HPV16 E2 plays an important role in viral gene regulation and replication. Fujii et al 2003 reported that nine peptides screened by phage display technique, could bind to HPV16 E2. This work aims to predict the binding conformations and interactions between the dodecapeptides and HPV16 E2 as well as to design novel peptide inhibitors that are capable of binding to HPV16 E2 and disrupting the transcriptional regulator E1-E2 complex formation, using computational protein design techniques. ClusPro Web Server was used to dock these peptides to E2. The ranking of the predicted binding affinities of the peptides is consistent to that of the experimental results; and peptide4 is the best E2 binder. Therefore, small peptides were designed based on peptide4 (TWFWPYPYPHLP). Trp4 of peptide4 was mutated to His, Asn and Ser, Tyr6 of peptide4 was mutated to Lys, Asn and Arg. Five newly designed peptides that showed lower binding energy to HPV16 E2 than that of peptide4, were selected for in vitro experiments. The HPV16 E1 and E2 were expressed and purified in Escherichia coli. Enzyme- linked immunosorbent assay was used to test whether the designed peptides could bind to HPV16 E2 and disrupt the E1-E2 complex formation better than peptide4. Y6R, W4H_Y6R and W4H peptides could bind better to HPV16 E2 than peptide4 did. Moreover, these three peptides are more effectively inhibited E1-E2 complex formation than peptide 4.