Kaposi's sarcoma-associated herpesvirus viral protein kinase interacts with RNA helicase a and regulates host gene expression.

RNA helicase A (RHA) containing the DExH motif is a human homolog of maleless protein that regulates expression of genes located in the Drosophila X chromosome during dosage compensation. RHA exerts helicase activity that unwinds double-stranded RNA and DNA to a single-strand form. The protein acts as a bridging factor mediating interactions of CBP/p300 and RNA pol II, and consequently affects gene expression. Kaposi's sarcoma-associated herpesvirus (KSHV) is a member of the gamma-herpesvirus subfamily that causes several disorders. The majority of herpesviruses commonly encode predicted viral protein kinases. KSHV open reading frame 36 (ORF36) codes for protein kinase domains, and functions as a serine/threonine protein kinase. KSHV ORF36 is classified as a late gene, as it is expressed during lytic replication and localized in the nuclei of KSHV-infected cells. Recent studies show that viral protein kinase (vPK) interacts with cellular proteins. In this study, we determined the cellular localization of vPK in KSHV-infected BCBL-1 cells using confocal microscopy. Proteomic analysis indicates that cellular proteins interacted with vPK, and co-immunoprecipitation reactions further reveal interactions between vPK and RHA. Moreover, KSHV vPK appeared to regulate the transcriptional activation of Cre promoter, and plays an important role in cellular transcription of RHA.