Open AccessCharacterization of the Nucleocytoplasmic Transport Mechanisms of Epstein-Barr Virus BFLF2
Author(s) -
Meili Li,
Tao Chen,
Xiaofang Zou,
Xu Zuo,
Yuanfang Wang,
Ping Wang,
Xiaowen Ou,
Yiwen Li,
Daixiong Chen,
Tao Peng,
Yao Wang,
Mingsheng Cai
Publication year - 2018
Publication title -
cellular physiology and biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.486
H-Index - 87
eISSN - 1421-9778
pISSN - 1015-8987
DOI - 10.1159/000495641
Subject(s) - nuclear transport , importin , nuclear localization sequence , nls , nuclear export signal , biology , microbiology and biotechnology , subcellular localization , cytoplasm , nuclear pore , cell nucleus , transfection , virology , cell culture , genetics
Background/Aims: Epstein-Barr virus (EBV) BFLF2, the homologue of herpes simplex virus 1 (HSV-1) UL31, is crucial for the efficient viral DNA packaging and primary egress across the nuclear membrane. However, we still do not know its subcellular transport mechanisms. Methods: Interspecies heterokaryon assays were utilized to detect the nucleocytoplasmic shuttling of BFLF2, and mutation analysis, plasmid transfection and fluorescence microscopy assays were performed to identify the functional nuclear localization sequence (NLS) and nuclear export sequence (NES) of BFLF2 in live cells. Furthermore, the nuclear import and export of BFLF2 were assessed by confocal microscopy, co-immunoprecipitation and immunoblot assays. Results: BFLF2 was confirmed to shuttle between the nucleus and cytoplasm. Two predicted NESs were shown to be nonfunctional, yet we proved that the nuclear export of BFLF2 was mediated through transporter associated with antigen processing (TAP), but not chromosomal region maintenance 1 (CRM1) dependent pathway. Furthermore, one functional NLS, 22RRLMHPHHRNYTASKASAH40, was identified, and the aa22-23, aa22-25, aa28-30 and aa37-40 had an important role in the nuclear localization of BFLF2. Besides, the nuclear import of BFLF2 was demonstrated through Ran-, importin α7-, importin β1- and transportin-1-dependent mechanism that does not require importin α1, α3 and α5. Conclusion: These works are of significance for the further study of the functions of BFLF2 during EBV infection, as well as for further insights into the design of new antiviral drug target and vaccine development against EBV.