Interaction between W41 of the hepatitis B virus preS1 surface peptide and Y146/F274 of the cellular receptor molecule Na+/taurocholate co-transporting polypeptide is essential for virus entry.

The myristoylated preS1 domain (myr-preS1) of the hepatitis B virus (HBV) large surface protein is essential for binding to the receptor protein, Na+/taurocholate co-transporting polypeptide (NTCP), and for the subsequent internalization of the virus-receptor complex. NTCP, which is expressed in hepatocytes, plays a physiological role in hepatic bile acid transport. Recent cryo-electron microscopy structures of the myr-preS1-NTCP complex were used to analyze virus-receptor interactions at the molecular level. Several interaction domains with high binding energies have been identified, including the interaction between myr-preS1 tryptophan 41 (W41) and the NTCP residues tyrosine 146 and phenylalanine 274 (Y146/F274), which are located at a considerable distance from the physiological bile acid binding sites of NTCP. The Y146A/F274A mutant of NTCP retained bile acid transport function but showed a reduced myr-preS1 binding. The W41G myr-preS1 mutant exhibited reduced binding to wild-type NTCP. The Y146A/F274A NTCP mutant did not support in vitro HBV infection, and the W41G myr-preS1 peptide was less effective in blocking infection compared with the wild-type myr-preS1 peptide. In conclusion, the myr-preS1-W41/NTCP-Y146/F274 interaction site, characterized by high binding energy, is essential for HBV entry into hepatocytes. Because this domain is spatially distinct from the bile acid binding and translocation sites of NTCP, it presents an attractive receptor target site for structure-based development of virus-selective HBV entry inhibitors that preserve the physiological bile acid transport function of NTCP. SIGNIFICANCE STATEMENT: This study identified and validated a high energy interaction site between the hepatitis B virus and its receptor Na+/taurocholate co-transporting polypeptide that can be used for structure-based drug design of virus entry inhibitors.