
<ArticleTitle>Human <prot>hepatitis B virus polymerase</prot> interacts with the molecular chaperonin <prot>Hsp60</prot>.</ArticleTitle>
<AbstractText>Previous studies showed that <prot>hepatitis B virus polymerase</prot> (<prot>HBV Pol</prot>) interacts with host factors such as the <prot>Hsp90</prot> complex, which is a critical step in viral genome replication. In this report, we propose that another chaperone, <prot>Hsp60</prot>, interacts with human <prot>HBV Pol</prot> and that this is a very important step for maturation of human <prot>HBV Pol</prot> into the active state. In the immunoprecipitation of recombinant human <prot>HBV Pol</prot> expressed in insect cells with the recombinant baculovirus expression system, the 60-kDa protein was coimmunoprecipitated with <prot>Pol</prot> and the protein was identified as <prot>Hsp60</prot> through peptide sequencing and immunogenic analysis with an anti-<prot>Hsp60</prot> antibody. In vitro experiments showed that <prot>Hsp60</prot> strongly affected human <prot>HBV Pol</prot> activity in that (i) blocking of <prot>Hsp60</prot> by the protein-specific antibody reduced human <prot>HBV Pol</prot> activity, (ii) the activity was increased by addition of <prot>Hsp60</prot> in the presence of ATP, and (iii) ATP synergistically activated human <prot>HBV Pol</prot> with <prot>Hsp60</prot>. In vivo experiments showed that inhibition of <prot>Hsp60</prot> in cells by a mutant <prot>Hsp60</prot>, <prot>C Delta 540</prot>, resulted in the reduction of human <prot>HBV Pol</prot> activity. In summary, our results indicate that the interaction is significant for conversion of human <prot>HBV Pol</prot> into the active state.</AbstractText>
