| 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. |