IMR Press / FBL / Volume 14 / Issue 4 / DOI: 10.2741/3322

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
Kaposi's sarcoma-associated herpesvirus ORF57 in viral RNA processing
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1 HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1868, USA
Academic Editor:Zhi-Ming Zheng
Front. Biosci. (Landmark Ed) 2009, 14(4), 1516–1528; https://doi.org/10.2741/3322
Published: 1 January 2009
(This article belongs to the Special Issue Protein-RNA interactions in viral RNA processing)
Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 (MTA, mRNA transcript accumulation) is a multifunctional regulator of the expression of viral lytic genes. KSHV ORF57 is expressed during viral lytic infection and is essential for virus production. Like its homologues in the herpesvirus family, ORF57 promotes the accumulation (stabilization) and export of viral intronless RNA transcripts by a mechanism which remains to be defined. The ORF57-Aly/REF interaction plays only a small role in viral RNA export. Although other members of the family generally inhibit the splicing of cellular RNAs, KSHV ORF57 and EBV EB2, in sharp contrast, stimulate viral RNA splicing for the expression of viral intron-containing genes. The functions of KSHV ORF57 are independent of transcription and of other viral proteins; instead, these functions always rely on cellular components and occur in various protein-RNA complexes. ORF57 may synergize with KSHV ORF50 to transactivate a subset of viral promoters by an unknown mechanism. Thus, some functions of ORF57 have been conserved while others have diverged from its homologues as ORF57 adapted over evolution to KSHV biology and pathogenesis.

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