Positively charged sequences of human papillomavirus type 16 capsid proteins are sufficient to mediate gene transfer into target cells via the heparan sulfate receptor.

Using synthetic peptides we have shown that positively charged sequences present at the C terminus of the L1 protein and the N and C termini of the L2 protein of human papillomavirus type 16 (HPV-16) bind to both DNA and heparan sulfate receptors. Moreover, these short amino acid sequences are sufficient to mediate gene transfer in COS-7 cells. The L1 proteins of other HPVs were shown to contain one or two DNA- and heparin-binding sequences that have the capacity to transfer genes. These DNA-binding sequences also recognized the enhancing packaging sequence of bovine papillomavirus type 1. The results suggest that the L2 protein could participate in DNA packaging during maturation of virions.