Hydrophobic residues of terminal protein domain of hepatitis B virus polymerase contribute to distinct steps in viral genome replication.

Hepatitis B virus (HBV) replicates its DNA genome via reverse transcription. Precise roles of the terminal protein domain of HBV polymerase remain unknown. To gain insight, we created alanine substitution mutations at hydrophobic residues (i.e., tyrosine, tryptophan, and isoleucine), and then examined the extent by which these mutants carry out viral genome replication. Evidence indicated that three hydrophobic residues of the terminal protein domain (i.e., W74, Y147, and Y173) contribute to distinct steps of viral genome replication: the former two residues are important for viral DNA synthesis, while the latter is important for viral RNA encapsidation.