Kaposi's sarcoma-associated herpesvirus K-bZIP represses gene transcription via SUMO modification

Yoshihiro Izumiya, Thomas J. Ellison, Edward T.H. Yeh, Jae U. Jung, Paul A. Luciw, Hsing Jien Kung

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63 Citations (Scopus)

Abstract

Kaposi's sarcoma-associated herpesvirus (KSHV) is a human gammaherpesvirus implicated in AIDS-related neoplasms. Previously, we demonstrated that the early lytic gene product K-bZIP is a transcriptional represser that affects a subset of viral gene transcriptions mediated by the viral transactivator K-Rta (Y. Izumiya et al. J. Virol. 77:1441-1451, 2003). Sumoylation has emerged as an important posttranslational modification that affects the location and function of cellular and viral proteins and also plays a significant role in transcriptional repression along with Ubc9, the E2 SUMO conjugation enzyme. Here, we provide evidence that K-bZIP is sumoylated at the lysine 158 residue and associates with Ubc9 both in a cell-free system and in virus-infected BCBL-1 cells. Reporter assays showed that the expression of SUMO-specific protease 1 attenuated the transcriptional repression activity of K-bZIP. The expression of a K-bZIPK158R mutant, which was no longer sumoylated, exhibited the reduced transcriptional repression activity. This indicates that sumoylation plays an important part in the transcriptional repression activity of K-bZIP. Finally, chromatin immunoprecipitation experiments demonstrated that K-bZIP interacts with and recruits Ubc9 to specific KSHV promoters. Thus, our data indicate that K-bZIP is a SUMO adaptor, which recruits Ubc9 to specific viral target promoters, thereby exerting its transcriptional repression activity.

Original languageEnglish
Pages (from-to)9912-9925
Number of pages14
JournalJournal of Virology
Volume79
Issue number15
DOIs
Publication statusPublished - Aug 1 2005
Externally publishedYes

ASJC Scopus subject areas

  • Immunology
  • Virology

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