Requirement of the N-terminal residues of human cytomegalovirus UL112-113 proteins for viral growth and oriLyt-dependent DNA replication

• Published in: The journal of microbiology Vol. 53; no. 8; pp. 561 - 569
• Main Authors: Kim, Young-Eui, Park, Mi Young, Kang, Kyeong Jin, Han, Tae Hee, Lee, Chan Hee, Ahn, Jin-Hyun
• Format: Journal Article
• Language: English
• Published: Seoul The Microbiological Society of Korea 01.08.2015; Springer Nature B.V; 한국미생물학회
• Subjects: Biomedical and Life Sciences; Cytomegalovirus; Cytomegalovirus - physiology; Deoxyribonucleic acid; DNA; DNA polymerase; DNA Replication; DNA, Viral; DNA-Binding Proteins - physiology; DNA-directed DNA polymerase; Fibroblasts; Gene loci; genes; Genome, Viral; Genomes; Human cytomegalovirus; Human herpesvirus 5; Humans; Kinases; Life Sciences; microbial growth; Microbiology; phosphoproteins; Phosphoproteins - physiology; Plasmids; Protein Interaction Domains and Motifs; Proteins; Relocation; Residues; transcription factors; viral proteins; Viral Proteins - physiology; Virology; virus replication; Virus Replication - genetics; 생물학; South Korea; replication; UL44; self-interaction; HCMV; UL112-113
• ISSN: 1225-8873; 1976-3794
• DOI: 10.1007/s12275-015-5301-3

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.