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- Title
Amino Acid Substitution Analyses of the DNA Contact Region, Two Amphipathic α-Helices and a Recognition-Helix-Like Helix outside the Dimeric β-Barrel of Epstein-Barr Virus Nuclear Antigen 1.
- Authors
Fujita, Tomomichi; Ikeda, Masato; Kusano, Shuichi; Yamazaki, Makoto; Ito, Sayuri; Obayashi, Maya; Yanagi, Kazuo
- Abstract
Objectives and Methods: Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1), which is essential for EBV latency, homodimerizes and binds to the EBV replication origin, oriP. We analyzed the dimerization/DNA-binding domain of EBNA-1 by random and site-directed amino acid substitution. Results: Random point mutations that resulted in reduced DNA binding clustered in the DNA contact region (a.a. 461-473) and at or near the termini of α-helix II (514-527). Three substitutions of Gly in the DNA contact region each greatly reduced binding to a single binding site oligonucleotide. Substitutions at and near the termini of α-helix II diminished DNA binding. A helix-deforming substitution in α-helix I (477-489) blocked DNA binding. A helix-deforming substitution in α-helix III (568-582) abolished dimerization and DNA binding. Similarities in surface electrostatic properties and conserved amino acids were found between α-helix II and recognition helices of papillomavirus E2 proteins. Conclusions: The basic DNA contact region is crucial for the specific interaction of EBNA-1 with a single binding site. α-Helix I477 is indispensable for oriP binding, and α-helix III568 contributes to the homodimeric structure of EBNA-1. α-Helix II514 contributes to oriP binding, perhaps changing its alignment with DNA. Copyright © 2001 S. Karger AG, Basel
- Publication
Intervirology, 2001, Vol 44, Issue 5, p271
- ISSN
0300-5526
- Publication type
Article
- DOI
10.1159/000050058