HBc and HBe antigenicity and DNA-binding activity of major core protein P22 in hepatitis B virus core particles isolated from the cytoplasm of human liver cells.
Highly purified hepatitis B virus core particles were obtained in large amounts from the cytoplasm of infected human liver cells. This DNA polymerase-negative core preparation had only hepatitis B core antigen-specific antigenicity and showed a surprising stability. Two forms of a single protein of 22,000 molecular weight, P22, were resolved electrophoretically; the slower moving species, P22a, appeared to be a reduced form of the protein, and the faster moving species, P22b, could have represented a conformational isomer containing an intramolecular disulfide bond(s). The immunological properties and DNA-binding activity of the reduced form, P22a, were examined following separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by transfer onto nitrocellulose membranes (Western blotting). We found that the hepatitis B virus C gene protein shared the antigenic site responsible for both hepatitis B core and e antigen reactivity. We also demonstrated that the core protein(s) bound specifically the genomic hepatitis B virus DNA in comparison with a plasmid DNA (pBR322). This last observation was further substantiated by a radioimmunological method. P22a was also found to be phosphorylated in vitro by the endogenous protein kinase activity, copurified with the hepatitis B core antigen particles. These findings suggest that P22 is a multifunctional protein which is incorporated into core particles within the cytoplasm of the host cell before DNA encapsidation. A critical role of this protein in hepatitis B virus assembly is suggested.
Petit
M A
MA
Pillot
J
J
D003593:Cytoplasm / Q000382:microbiology; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D000939:Epitopes; D006509:Hepatitis B / Q000382:microbiology; D006511:Hepatitis B Antigens / Q000276:immunology*; D006512:Hepatitis B Core Antigens / Q000276:immunology*; D006513:Hepatitis B e Antigens / Q000276:immunology*; D006515:Hepatitis B virus / Q000032:analysis* / Q000302:isolation & purification; D006801:Humans; D008099:Liver / Q000382:microbiology / Q000648:ultrastructure; D008970:Molecular Weight; D011494:Protein Kinases / Q000378:metabolism; D014758:Viral Core Proteins; D014764:Viral Proteins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D000939:Epitopes; D006511:Hepatitis B Antigens; D006512:Hepatitis B Core Antigens; D006513:Hepatitis B e Antigens; D014758:Viral Core Proteins; D014764:Viral Proteins; D011494:Protein Kinases