51
|
Avolio-Hunter TM, Lewis PN, Frappier L. Epstein-Barr nuclear antigen 1 binds and destabilizes nucleosomes at the viral origin of latent DNA replication. Nucleic Acids Res 2001; 29:3520-8. [PMID: 11522821 PMCID: PMC55891 DOI: 10.1093/nar/29.17.3520] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2001] [Revised: 07/09/2001] [Accepted: 07/17/2001] [Indexed: 11/12/2022] Open
Abstract
The EBNA1 protein of Epstein-Barr virus (EBV) activates latent-phase DNA replication by an unknown mechanism that involves binding to four recognition sites in the dyad symmetry (DS) element of the viral latent origin of DNA replication. Since EBV episomes are assembled into nucleosomes, we have examined the ability of Epstein-Barr virus nuclear antigen 1 (EBNA1) to interact with the DS element when it is assembled into a nucleosome core particle. EBNA1 bound to its recognition sites within this nucleosome, forming a ternary complex, and displaced the histone octamer upon competitor DNA challenge. The DNA binding and dimerization region of EBNA1 was sufficient for nucleosome binding and destabilization. Although EBNA1 was able to bind to nucleosomes containing two recognition sites from the DS element positioned at the edge of the nucleosome, nucleosome destabilization was only observed when all four sites of the DS element were present. Our results indicate that the presence of a nucleosome at the viral origin will not prevent EBNA1 binding to its recognition sites. In addition, since four EBNA1 recognition sites are required for both nucleosome destabilization and efficient origin activation, our findings also suggest that nucleosome destabilization by EBNA1 is important for origin activation.
Collapse
Affiliation(s)
- T M Avolio-Hunter
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, Ontario M5S 1A8, Canada
| | | | | |
Collapse
|
52
|
Schepers A, Ritzi M, Bousset K, Kremmer E, Yates JL, Harwood J, Diffley JF, Hammerschmidt W. Human origin recognition complex binds to the region of the latent origin of DNA replication of Epstein-Barr virus. EMBO J 2001; 20:4588-602. [PMID: 11500385 PMCID: PMC125560 DOI: 10.1093/emboj/20.16.4588] [Citation(s) in RCA: 180] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Epstein-Barr virus (EBV) replicates in its latent phase once per cell cycle in proliferating B cells. The latent origin of DNA replication, oriP, supports replication and stable maintenance of the EBV genome. OriP comprises two essential elements: the dyad symmetry (DS) and the family of repeats (FR), both containing clusters of binding sites for the transactivator EBNA1. The DS element appears to be the functional replicator. It is not yet understood how oriP-dependent replication is integrated into the cell cycle and how EBNA1 acts at the molecular level. Using chromatin immunoprecipitation experiments, we show that the human origin recognition complex (hsORC) binds at or near the DS element. The association of hsORC with oriP depends on the DS element. Deletion of this element not only abolishes hsORC binding but also reduces replication initiation at oriP to background level. Co-immunoprecipitation experiments indicate that EBNA1 is associated with hsORC in vivo. These results indicate that oriP might use the same cellular initiation factors that regulate chromosomal replication, and that EBNA1 may be involved in recruiting hsORC to oriP.
Collapse
Affiliation(s)
- Aloys Schepers
- Department of Gene Vectors and
Institute for Immunology, National Research Centre for Environment and Health, Marchioninistrasse 25, D-81377 München, Germany, Department of Cancer Genetics, Roswell Park Cancer, Elm and Carlton Streets, Buffalo, NY 14263, USA and Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms EN6 3LD, UK Present address: GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK Corresponding author e-mail:
| | | | | | - Elisabeth Kremmer
- Department of Gene Vectors and
Institute for Immunology, National Research Centre for Environment and Health, Marchioninistrasse 25, D-81377 München, Germany, Department of Cancer Genetics, Roswell Park Cancer, Elm and Carlton Streets, Buffalo, NY 14263, USA and Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms EN6 3LD, UK Present address: GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK Corresponding author e-mail:
| | - John L. Yates
- Department of Gene Vectors and
Institute for Immunology, National Research Centre for Environment and Health, Marchioninistrasse 25, D-81377 München, Germany, Department of Cancer Genetics, Roswell Park Cancer, Elm and Carlton Streets, Buffalo, NY 14263, USA and Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms EN6 3LD, UK Present address: GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK Corresponding author e-mail:
| | - Janet Harwood
- Department of Gene Vectors and
Institute for Immunology, National Research Centre for Environment and Health, Marchioninistrasse 25, D-81377 München, Germany, Department of Cancer Genetics, Roswell Park Cancer, Elm and Carlton Streets, Buffalo, NY 14263, USA and Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms EN6 3LD, UK Present address: GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK Corresponding author e-mail:
| | - John F.X. Diffley
- Department of Gene Vectors and
Institute for Immunology, National Research Centre for Environment and Health, Marchioninistrasse 25, D-81377 München, Germany, Department of Cancer Genetics, Roswell Park Cancer, Elm and Carlton Streets, Buffalo, NY 14263, USA and Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms EN6 3LD, UK Present address: GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK Corresponding author e-mail:
| | | |
Collapse
|