KSHV encoded viral processivity factor, ORF59, regulates multiple pathways for viral replication
AuthorDingman, Kammi Lynn
AdvisorVerma, Subhash C
Biochemistry and Molecular Biology
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Kaposi’s Sarcoma-Associated Herpesvirus (KSHV), or human herpesvirus 8 (HHV-8), is a tumorigenic herpesvirus tightly linked with various human malignancies including Kaposi’s Sarcoma, Primary Effusion Lymphomas (PELs), and Multicentric Castleman’s Disease. Immunocompetent individuals infected with KSHV are asymptomatic, but the immunocompromised individuals are at risk for developing lethal cancers. ORF59, a DNA processivity factor of the viral DNA polymerase, is essential for lytic reactivation and is highly expressed during de novo primary infection. To better understand the role of ORF59, we performed an ORF59-immunoprecipitation from KSHV infected cells and identified ORF59 interacting proteins through protein sequencing and LC/MS spectrometry analysis. From a large number of ORF59 interacting proteins, we pursued few candidates for further study including host proteins Nucleolin and MCM4 in addition to viral protein, ORF57. Our characterization of the interaction between KSHV ORF59 and these associating factors yielded exciting new insights on host-virus interactions that we expect to be valuable for understanding KSHV pathogenesis. Nucleolin (NCL), involved in ribosome assembly, pre-mRNA metabolism, cytoplasmic RNA stability, and nucleo-cytoplasmic transport as well as ORF57, an mRNA transcript accumulation (MTA) viral early protein involved in posttranscriptional regulation, splicing of viral RNA transcripts, RNA stability, and transcriptional activation, bound specifically to ORF59. ORF59 also associated with minichromosome maintenance proteins (MCMs), a complex of DNA replication licensing factor required for cellular DNA replication.