Human RPB5, a subunit shared by eukaryotic nuclear RNA polymerases, binds human hepatitis B virus X protein and may play a role in X transactivation

J. H. Cheong, Min Kyung Yi, Y. Lin, S. Murakami

Research output: Contribution to journalArticle

235 Citations (Scopus)

Abstract

The X gene of human hepatitis B virus encodes the polypeptide HBx which transactivates viral and host genes through a variety of cis-acting enhancer elements present in RNA polymerases I, II and III promoters. To better understand the mechanism of X transactivation, we cloned cDNAs of proteins that bind HBx. Here we demonstrate that one of these cDNAs is a full-length cDNA of human RPB5, a subunit shared by RNA polymerases. The HBx transactivation domain and the central region of human RPB5 were necessary for the specific binding of the two proteins as shown by: (i) in vitro assays using deletion mutants of fusion proteins; (ii) in vivo assays which detect associated proteins by co-immunoprecipitation of the non-fused proteins from transfected HepG2 cells. Over-expressed HBx seemed to associate with assembled forms of endogenous human RPB5 in HBx-transfected cells, since the endogenous RPB5 co-immunoprecipitated with HBx. The HBx binding region of human RPB5 by itself stimulated chloramphenicol acetyltransferase activities from several different reporters having X-responsive element(s). Our results support the idea that the interaction of HBx and human RPB5 can facilitate HBx transactivation and that human RPB5 has a domain which can communicate with transcriptional regulators.

Original languageEnglish (US)
Pages (from-to)143-150
Number of pages8
JournalEMBO Journal
Volume14
Issue number1
StatePublished - 1995
Externally publishedYes

Fingerprint

Nuclear RNA
DNA-Directed RNA Polymerases
Transcriptional Activation
Complementary DNA
Proteins
Assays
Genes
RNA Polymerase I
Chloramphenicol O-Acetyltransferase
Viruses
RNA Polymerase III
Viral Genes
RNA Polymerase II
Fusion reactions
Hep G2 Cells
Mutant Proteins
hepatitis B virus X protein
Immunoprecipitation
Hepatitis B virus
Peptides

Keywords

  • HBV X protein
  • Human RPB5
  • RNA polymerases
  • Transactivation
  • X-associated protein

ASJC Scopus subject areas

  • Cell Biology
  • Genetics

Cite this

Human RPB5, a subunit shared by eukaryotic nuclear RNA polymerases, binds human hepatitis B virus X protein and may play a role in X transactivation. / Cheong, J. H.; Yi, Min Kyung; Lin, Y.; Murakami, S.

In: EMBO Journal, Vol. 14, No. 1, 1995, p. 143-150.

Research output: Contribution to journalArticle

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AU - Lin, Y.

AU - Murakami, S.

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