The Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Binds to Specific Sequences at the Left End of the Viral Genome through Its Carboxy-Terminus

Abstract

Latent infection by members of the gammaherpesvirus family is typically characterized by stable episomal maintenance of genomic viral DNA. In the case of Epstein--Barr virus (EBV), this is dependent upon binding of the Epstein-Barr nuclear antigen 1 (EBNA1) to sites which lie within the origin of plasmid replication (OriP). The recently discovered Kaposi's sarcoma-associated herpesvirus (KSHV) encodes the latency-associated nuclear antigen (LANA), which appears to be important for supporting the latent infection of human cells by KSHV. The present work describes site-specific binding of the LANA protein to multiple different elements at the left end of the genome, a region which appears to be critical for maintenance of KSHV episomes. Of the three sites, terminal LANA-binding region 4 (TLBR4) binds LANA with the highest affinity when compared to the other sites. Further characterization of this cis-acting element by mutagenesis studies indicates that the minimal TLBR4-binding sequence is represented by a 13-bp sequence 5prime prime or minute CGCCCGGGCATGG 3prime prime or minute. Furthermore, this specific binding to TLBR4 was mediated by the distal 200 amino acid C-terminus of the LANA protein.

Kaposi's Sarcoma-Associated Herpesvirus-Encoded Latency-Associated Nuclear Antigen Modulates K1 Expression through Its cis -Acting Elements within the Terminal Repeats

“…Since LANA is expressed in almost all KSHV-positive cells and important for tethering of the viral genome by binding to the LANA binding sequence (2,10,19,20,26), we hypothesized that LANA may have a role in regulation of K1 expression. We digested cosmid Z6 of KSHV with BamHI and NotI and cloned K1p as described in the schematic (Fig.…”

“…Regulation of K1 expression during latent and lytic replication cycles. LANA tethers the viral genome to the host chromosome through binding to its cognate sequence within the terminal repeat (TR) (2,10). Binding of LANA to the terminal repeat promoter region of K1 down-regulates K1 expression and therefore down-regulates K1-mediated signaling and thus helps in maintaining latency.…”

Kaposi's sarcoma herpesvirus-encoded latency-associated nuclear antigen stabilizes intracellular activated Notch by targeting the Sel10 protein

“…Cells latently infected by KSHV express a limited number of viral genes, including latency-associated nuclear antigen (LANA) (7). Several important functions have been highlighted for LANA, including maintenance of the viral episome (8)(9)(10). LANA interacts with the tumor suppressors p53 and pRb, leading to the inhibition of apoptosis and cell cycle deregulation mediated by these tumor suppressors (11,12).…”

The Viral Etiology of AIDS‐Associated Malignancies

“…The KSHV LANA is a nuclear phosphoprotein that is important for the maintenance of viral latency (Dittmer et al, 1998). It has been shown to bind to the terminal repeat region of the viral genome and tethered the viral episome to the host chromosome so that it can be maintained during cellular mitotic replication and segregation (Ballestas et al, 1999;Cotter et al, 2001). LANA is a multifunctional viral protein and can bind to a number of cellular proteins.…”