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.
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.[1]References
- 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, M., Lin, Y., Murakami, S. EMBO J. (1995) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
