title: Transcriptional repression of K-Rta by Kaposi's sarcoma-associated herpesvirus K-bZIP is not required for oriLyt-dependent DNA replication.
abstract: Kaposi's sarcoma-associated herpesvirus origin-dependent DNA replication requires the core replication proteins plus K-Rta and K-bZIP. To determine which K-bZIP protein domains contribute to oriLyt-dependent DNA replication and facilitate suppression of K-Rta-mediated transcriptional activation, we generated a series of deletion constructs and site-directed mutations within the K-bZIP ORF. Mutation of key leucine residues within the putative leucine zipper (LZ) motif eliminated the ability of the protein to homodimerize and complement oriLyt-dependent DNA replication. Deletion of the basic amino acid region (BR) or LZ domain did not affect the ability of K-bZIP to bind to K-Rta indicating that either region contributes to heterodimerization with K-Rta. However, deletions or mutations introduced into both the LZ and BR resulted in elimination of the suppressive activity of K-bZIP even in the presence of a K-bZIP-K-Rta interaction. Interestingly, mutants that lacked the ability to suppress K-Rta transactivation were still capable of complementing oriLyt-dependent DNA replication, indicating that this activity does not contribute to the DNA synthesis-related activity of K-bZIP.
authors: University of Nevada, Reno School of Medicine, Department of Microbiology and Immunology and the Cell and Molecular Biology Graduate Program, Howard Bldg. 210, Reno, NV 89557, USA.
authors: Cyprian
authors: C
authors: Rossetto
authors: Yang
authors: Y
authors: Gao
authors: Irena
authors: I
authors: Yamboliev
authors: Iva
authors: I
authors: Papousková
authors: Gregory
authors: G
authors: Pari
mesh_terms: D000818:Animals; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D004261:DNA Replication / Q000235:genetics / Q000502:physiology*; D004279:DNA, Viral / Q000096:biosynthesis / Q000235:genetics; D019281:Dimerization; D005814:Genes, Viral; D005816:Genetic Complementation Test; D019288:Herpesvirus 8, Human / Q000235:genetics / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D016350:Leucine Zippers / Q000235:genetics / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D015533:Transcriptional Activation; D014709:Vero Cells; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; D004279:DNA, Viral; D017874:Immediate-Early Proteins; C118265:K8 protein, Human herpesvirus 8; D012097:Repressor Proteins; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014764:Viral Proteins