Kaposi's sarcoma-associated herpesvirus (human herpesvirus 8) replication and transcription factor activates the K9 (vIRF) gene through two distinct cis elements by a non-DNA-binding mechanism.
The replication and transcription activator (RTA) of Kaposi's sarcoma-associated herpesvirus (KSHV), or human herpesvirus 8, a homologue of Epstein-Barr virus BRLF1 or Rta, is a strong transactivator and inducer of lytic replication. RTA acting alone can induce lytic replication of KSHV in infected cell lines that originated from primary effusion lymphomas, leading to virus production. During the lytic replication process, RTA activates many kinds of genes, including polyadenylated nuclear RNA, K8, K9 (vIRF), ORF57, and so on. We focused here on the mechanism of how RTA upregulates the K9 (vIRF) promoter and identified two independent cis-acting elements in the K9 (vIRF) promoter that responded to RTA. These elements were finally confined to the sequence 5'-TCTGGGACAGTC-3' in responsive element (RE) I-2B and the sequence 5'-GTACTTAAAATA-3' in RE IIC-2, both of which did not share sequence homology. Multiple factors bound specifically with these elements, and their binding was correlated with the RTA-responsive activity. Electrophoretic mobility shift assay with nuclear extract from infected cells and the N-terminal part of RTA expressed in Escherichia coli, however, did not show that RTA interacted directly with these elements, in contrast to the RTA responsive elements in the PAN/K12 promoter region, the ORF57/K8 promoter region. Thus, it was likely that RTA could transactivate several kinds of unique cis elements without directly binding to the responsive elements, probably through cooperation with other DNA-binding factors.
Ueda
Keiji
K
Department of Microbiology, Osaka University School of Medicine, Suita, Osaka, Japan. kueda@micro.med.osaka-u.ac.jp
Ishikawa
Kayo
K
Nishimura
Ken
K
Sakakibara
Shuhei
S
Do
Eunju
E
Yamanishi
Koichi
K
D001402:B-Lymphocytes / Q000821:virology; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D019288:Herpesvirus 8, Human / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000502:physiology*; D050835:Interferon Regulatory Factors; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics* / Q000502:physiology*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D050835:Interferon Regulatory Factors; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014157:Transcription Factors; D014764:Viral Proteins; C413486:viral interferon regulatory factors