Protein Domain : DNA helicase E1, N-terminal, Papillomavirus IPR014000

Type	Domain
Description	Papillomaviruses (PPV) are a large family of DNA tumour viruses which give rise to warts in their host species. The helicase E1 protein is an ATP-dependent DNA helicase required for initiation of viral DNA replication [ , ]. It forms a complex with the viral E2 protein, which is a site-specific DNA-binding transcriptional activator. The E1-E2 complex binds to the replication origin which contains binding sites for both proteins [].The E1 protein is a 70kDa polypeptide with a centrally-located DNA-binding domain and a C-terminal ATPase/helicase domain. It binds specific 18 bp DNA sequences at the origin of replication, melts the DNA duplex and functions as a 3' to 5' helicase [ ]. In addition to E2 it also interacts with DNA polymerase alpha and replication protein A to effect DNA replication. The DNA-binding domain forms a five-stranded antiparallel beta sheet bordered by four loosely packed alpha helices on one side and two tightly packed helices on the other []. Two structural modules within this domain, an extended loop and a helix, contain conserved residues and are critical for DNA binding. In solution E1 is a monomer, but binds DNA as a dimer. Recruitment of more E1 subunits to the complex leads to melting of the origin and ultimately to the formation of an E1 hexamer with helicase activity [].This entry represents the N-terminal region of E1, which contains the nuclear localisation signal.
Short Name	PPV_DNA_helicase_E1_N