title: Bub1 in Complex with LANA Recruits PCNA To Regulate Kaposi's Sarcoma-Associated Herpesvirus Latent Replication and DNA Translesion Synthesis.
abstract: Latent DNA replication of Kaposi's sarcoma-associated herpesvirus (KSHV) initiates at the terminal repeat (TR) element and requires trans-acting elements, both viral and cellular, such as ORCs, MCMs, and latency-associated nuclear antigen (LANA). However, how cellular proteins are recruited to the viral genome is not very clear. Here, we demonstrated that the host cellular protein, Bub1, is involved in KSHV latent DNA replication. We show that Bub1 constitutively interacts with proliferating cell nuclear antigen (PCNA) via a highly conserved PIP box motif within the kinase domain. Furthermore, we demonstrated that Bub1 can form a complex with LANA and PCNA in KSHV-positive cells. This strongly indicated that Bub1 serves as a scaffold or molecular bridge between LANA and PCNA. LANA recruited PCNA to the KSHV genome via Bub1 to initiate viral replication in S phase and interacted with PCNA to promote its monoubiquitination in response to UV-induced damage for translesion DNA synthesis. This resulted in increased survival of KSHV-infected cells.
  
  
  OBJECTIVE
  During latency in KSHV-infected cells, the viral episomal DNA replicates once each cell cycle. KSHV does not express DNA replication proteins during latency. Instead, KSHV LANA recruits the host cell DNA replication machinery to the replication origin. However, the mechanism by which LANA mediates replication is uncertain. Here, we show that LANA is able to form a complex with PCNA, a critical protein for viral DNA replication. Furthermore, our findings suggest that Bub1, a spindle checkpoint protein, serves as a scaffold or molecular bridge between LANA and PCNA. Our data further support a role for Bub1 and LANA in PCNA-mediated cellular DNA replication processes as well as monoubiquitination of PCNA in response to UV damage. These data reveal a therapeutic target for inhibition of KSHV persistence in malignant cells.
authors.affiliation: Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Hem Chandra
authors.initials: HC
authors.lastname: Jha
authors.affiliation: Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA erle@mail.med.upenn.edu.
authors.forename: Erle S
authors.initials: ES
authors.lastname: Robertson
mesh_terms: D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D016679:Genome, Viral; D019288:Herpesvirus 8, Human / Q000235:genetics* / Q000378:metabolism; D054884:Host-Pathogen Interactions; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism* / Q000821:virology; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase; D015398:Signal Transduction; D020079:Terminal Repeat Sequences; D054875:Ubiquitination; D017735:Virus Latency; D014779:Virus Replication
chemical_list: D000956:Antigens, Viral; D004279:DNA, Viral; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins; C109540:latency-associated nuclear antigen; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases