The EBNA-2 N-Terminal Transactivation Domain Folds into a Dimeric Structure Required for Target Gene Activation

PLoS Pathogens

Michael Sattler¹  Sybille Thumann¹  Elfriede Nössner¹  Janosch Hennig²  Bettina Kempkes³  Anders Friberg⁴  Peijian Zou⁴  Paul D. Ling⁴ 

[1] Center for Integrated Protein Science Munich at Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Garching, Germany;Department of Gene Vectors, Hematologikum, Helmholtz Zentrum München, National Research Center for Environmental Health, München, Germany;Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China;Institute of Structural Biology, Helmholtz Zentrum München, National Research Center for Environmental Health, Neuherberg, Germany

关键词: Dimerization;    Dimers (Chemical physics);    Transactivation;    DNA-binding proteins;    Epstein-Barr virus;    B cells;    Protein structure;    Protein domains;   

DOI  :  10.1371/journal.ppat.1004910

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Epstein-Barr virus (EBV) is a γ-herpesvirus that may cause infectious mononucleosis in young adults. In addition, epidemiological and molecular evidence links EBV to the pathogenesis of lymphoid and epithelial malignancies. EBV has the unique ability to transform resting B cells into permanently proliferating, latently infected lymphoblastoid cell lines. Epstein-Barr virus nuclear antigen 2 (EBNA-2) is a key regulator of viral and cellular gene expression for this transformation process. The N-terminal region of EBNA-2 comprising residues 1-58 appears to mediate multiple molecular functions including self-association and transactivation. However, it remains to be determined if the N-terminus of EBNA-2 directly provides these functions or if these activities merely depend on the dimerization involving the N-terminal domain. To address this issue, we determined the three-dimensional structure of the EBNA-2 N-terminal dimerization (END) domain by heteronuclear NMR-spectroscopy. The END domain monomer comprises a small fold of four β-strands and an α-helix which form a parallel dimer by interaction of two β-strands from each protomer. A structure-guided mutational analysis showed that hydrophobic residues in the dimer interface are required for self-association in vitro. Importantly, these interface mutants also displayed severely impaired self-association and transactivation in vivo. Moreover, mutations of solvent-exposed residues or deletion of the α-helix do not impair dimerization but strongly affect the functional activity, suggesting that the EBNA-2 dimer presents a surface that mediates functionally important intra- and/or intermolecular interactions. Our study shows that the END domain is a novel dimerization fold that is essential for functional activity. Since this specific fold is a unique feature of EBNA-2 it might provide a novel target for anti-viral therapeutics.

【 授权许可】

CC BY