Structure of the E2 DNA-binding domain from human papillomavirus serotype 31 at 2.4 angstrom

The papillomaviruses are a family of small double-stranded DNA viruses whic h exclusively infect epithelial cells and stimulate the proliferation of th ose cells. A key protein within the papillomavirus life-cycle is known as t he E2 (Early 2) protein and is responsible for regulating viral transcripti on from all viral promoters as well as for replication of the papillomaviru s genome in tandem with another protein known as El. The E2 protein itself consists of three functional domains: an N-terminal trans-activation domain , a proline-rich linker, and a C-terminal DNA-binding domain. The first cry stal structure of the human papillomavirus, serotype 31 (HPV-31), E2 DNA-bi nding domain has been determined at 2.4 Angstrom resolution. The HPV DNA-bi nding domain monomer consists of two beta-alpha-beta repeats of approximate ly equal length and is arranged as to have an antiparallel beta-sheet flank ed by the two alpha-helices. The monomers form the functional in vivo dimer by association of the beta-sheets of each monomer so as to form an eight-s tranded anti-parallel beta-barrel at the center of the dimer, with the alph a-helices lining the outside of the barrel. The overall structure of HVP-31 E2 DNA-binding domain is similar to both the bovine papillomavirus E2-bind ing domain and the Epstein-Barr nuclear antigen-1 DNA-binding domain.