HBV polymerase interacts independently with N-terminal and C-terminal fragments of Hsp90beta

Hsp90 is an abundant chaperone protein that assists the folding of specific proteins, such as steroid receptors, protein kinases, and so on, for their proper function. TP and RT domains of HBV polymerase have been also shown to be associated with Hsp90. Therefore, the identification of the binding sites within Hsp90, responsible for forming Hsp90/HBV Pol complex, is important for the understanding of HBV replication. In this study, cotransfection and immunoprecipitation experiments were performed to localize the binding sites of HBV pol to Hsp90. Our data show that HBV pol interact independently with both N-terminal and C-terminal fragments of Hsp90. Further analysis showed that N-terminal fragment (1-302) of Hsp90 interacts with both TP and RT domains of HBV pol, whereas C-terminal fragment (438-723) interacts with only RT domain. In conclusion, we showed that HBV pol independently interacts with N-terminal and C-terminal fragments, but not the middle fragment (327-438) of Hsp90.