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J Virol, March 1998, p. 1994-2001, Vol. 72, No. 3
Department of Biochemistry and Molecular
Genetics, Schools of Medicine and Dentistry, University of Alabama
at Birmingham, Birmingham, Alabama 35294-0005
Received 27 August 1997/Accepted 9 December 1997
The E1 and E2 proteins are the only virus-encoded factors required
for human papillomavirus (HPV) DNA replication. The E1 protein is a DNA
helicase responsible for initiation of DNA replication at the viral
origin. Its recruitment to the origin is facilitated by binding to E2,
for which specific recognition elements are located at the origin. The
remaining replication functions for the virus, provided by the host
cell's replication machinery, may be mediated by further interactions
with E1 and E2. Histone H1 was identified as an HPV type 11 (HPV-11)
E1-binding protein by far-Western blotting and by microsequence
analyses of a 34-kDa protein purified by E1 affinity chromatography. E1
also bound in vitro to H1 isolated under native conditions in
association with intact nucleosomes. In addition, E1 and H1 were
coimmunoprecipitated by an E1 antiserum from a nuclear extract prepared
from cells expressing recombinant E1. Bound H1 was displaced from
HPV-11 DNA by the addition of E1, suggesting that E1 can promote
replication initiation and elongation by alteration of viral chromatin
structure and disruption of nucleosomes at the replication fork.
Furthermore, a region of the HPV-11 genome containing the origin of
replication was identified which had weaker affinity for H1 than that
of the remaining genome. This result suggests that the presence of a DNA structure at or near the HPV origin facilitates initiation of DNA
replication by exclusion of H1. These results are similar to those of
studies of simian virus 40 DNA replication, in which a large T
antigen-H1 interaction and an H1-resistant region at the origin of DNA
replication have also been demonstrated.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Association of the Human Papillomavirus Type 11 E1 Protein with Histone H1
*
Corresponding author. Mailing address: Department of
Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, 1918 University Blvd., Rm. 460 MCLM, Birmingham, AL 35294-0005. Phone: (205) 934-4734. Fax: (205)
934-0758. E-mail: jengler{at}bmg.bhs.uab.edu.
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