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 = 진핵세포의 RNA 중합효소의 한 구성성분인 RPB5가 B형간염바이러스 X 단백질과 결합하여 X 전사활성화를 조절하는 기작

다국어 초록 (Multilingual 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 RPBS 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.

목차 (Table of Contents)

• Abstract = 143
• Introduction = 143
• Results = 143
• Cloning of cDNAs encoding HBx-associated proteins = 143
• HBx associated with human RPB5 in vitro = 144
• HBx associates with human RPB5 in transfected HepG2 cells = 146
• Transactiving ability of the HBx binding region of human RPB5 = 147
• Discussion = 149
• Materials and methods = 149
• Plasmid constructions = 149
• Cloning of cDNAs encoding X-associated proteins = 149
• Transfection and CAT assay = 150
• Western blotting and immunoprecipitation = 150
• Acknowledgements = 150
• References = 150