DNA-binding activity of hepatitis B e antigen polypeptide lacking the protaminelike sequence of nucleocapsid protein...

The characteristics of binding of hepatitis B core antigen (HBcAg) and hepatitis B e antigen (HBeAg) polypeptides to hepatitis B virus (HBV) DNA were analyzed. HBcAg polypeptide from recombinant HBV core particles and HBeAg polypeptide from partially purified serum HBeAg were prepared and verified to have molecular weights of 21,500 (P21.5) and of 17,000 (P17) and 18,000 (P18), respectively, by immunoblot analysis. By reaction of these proteins on a nitrocellulose membrane with cloned 32P-HBV DNA, it was revealed that the HBeAg polypeptide, which lacks the C-terminal 34 amino acids of P21.5, as well as the HBcAg polypeptide, bound to the DNA. The secondary structures of nucleocapsid proteins of HBV, woodchuck hepatitis virus, and ground squirrel hepatitis virus were predicted by the Garnier algorithm. Amino acid sequences which, in addition to those of the C-terminal regions, may contribute to binding were proposed to be the 21-amino-acid residues located at amino acids 100 to 120 of the nucleocapsid proteins of these hepadnaviruses.