title: Epstein-Barr nuclear antigen 1 (EBNA1)-dependent recruitment of origin recognition complex (Orc) on oriP of Epstein-Barr virus with purified proteins: stimulation by Cdc6 through its direct interaction with EBNA1.
abstract: Origin recognition complex (Orc) plays an essential role in directing assembly of prereplicative complex at selective sites on chromosomes. However, Orc from vertebrates is reported to bind to DNA in a sequence-nonspecific manner, and it is still unclear how it selects specific genomic loci and how Cdc6, another conserved AAA(+) factor known to interact with Orc, participates in this process. Replication from oriP, the latent origin of Epstein-Barr virus, provides an excellent model system for the study of initiation on the host chromosomes because it is known to depend on prereplicative complex factors, including Orc and Mcm. Here, we show that Orc is recruited selectively at the essential dyad symmetry element in nuclear extracts in a manner dependent on EBNA1, which specifically binds to dyad symmetry. With purified proteins, EBNA1 can recruit both Cdc6 and Orc independently on a DNA containing EBNA1 binding sites, and Cdc6 facilitates the Orc recruitment by EBNA1. Purified Cdc6 directly binds to EBNA1, whereas association of Orc with EBNA1 requires the presence of the oriP DNA. Nuclease protection assays suggest that Orc associates with DNA segments on both sides adjacent to the EBNA1 binding sites and that this process is stimulated by the presence of Cdc6. Thus, EBNA1 can direct localized assembly of Orc in a process that is facilitated by Cdc6. The possibility of similar modes of recruitment of Orc/Cdc6 at the human chromosomal origins will be discussed.
authors.affiliation: Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Moriyama
authors.forename: Naoko
authors.initials: N
authors.lastname: Yoshizawa-Sugata
authors.forename: Chikashi
authors.initials: C
authors.lastname: Obuse
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tsurimoto
authors.forename: Hisao
authors.initials: H
authors.lastname: Masai
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D018741:Replication Origin; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C103706:CDC6 protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C402640:EBNA-LP protein, Human herpesvirus 4; D009687:Nuclear Proteins; D051738:Origin Recognition Complex; D021122:Protein Subunits; D014764:Viral Proteins