Title |
Requirement of the N-terminal residues of human cytomegalovirus UL112-113 proteins for viral growth and oriLyt-dependent DNA replication |
Author |
Young-Eui Kim1, Mi Young Park1, Kyeong Jin Kang2, Tae Hee Han1, Chan Hee Lee3, and Jin-Hyun Ahn1* |
Address |
1Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Republic of Korea, 2Department of Anatomy and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Republic of Korea, 3Division of Life Sciences, Chungbuk National University, Cheongju 362-763, Republic of Korea |
Bibliography |
Journal of Microbiology, 53(8),561-569, 2015,
|
DOI |
10.1007/s12275-015-5301-3
|
Key Words |
HCMV, UL112-113, self-interaction, replication,
UL44 |
Abstract |
The UL112-113 region of the human cytomegalovirus (HCMV)
genome encodes four phosphoproteins of 34, 43, 50, and 84
kDa that promote viral DNA replication. Co-transfection
assays have demonstrated that self-interaction of these proteins
via the shared N-termini is necessary for their intranuclear
distribution as foci and for the efficient relocation
of a viral DNA polymerase processivity factor (UL44) to the
viral replication sites. However, the requirement of UL112-
113 N-terminal residues for viral growth and DNA replication
has not been fully elucidated. Here, we investigated
the effect of deletion of the N-terminal regions of UL112-
113 proteins on viral growth and oriLyt-dependent DNA
replication. A deletion of the entire UL112 region or the region
encoding the 25 N-terminal amino-acid residues from
the HCMV (Towne strain) bacmid impaired viral growth
in bacmid-transfected human fibroblast cells, indicating their
requirement for viral growth. In co-immunoprecipitation
assays using the genomic gene expressing the four UL112-
113 proteins together, the 25 N-terminal amino-acid residues
were found to be necessary for stable expression of UL112-
113 proteins and their self-interaction. These residues were
also required for efficient binding to and relocation of UL44,
but not for interaction with IE2, an origin-binding transcription
factor. In co-transfection/replication assays, replication
of the oriLyt-containing plasmid was promoted by
expression of intact UL112-113 proteins, but not by the expression
of 25-amino-acid residue-deleted proteins. Our
results demonstrate that the 25 N-terminal amino-acid residues
of UL112-113 proteins that mediate self-interaction
contribute to viral growth by promoting their binding to
UL44 and the initiation of oriLyt-dependent DNA replication. |