title: Structure of hepatitis B Dane particle DNA and nature of the endogenous DNA polymerase reaction.
abstract: The circular DNA of hepatitis B Dane particles, which serves as the primer/template for an endogenous DNA polymerase, was analyzed by electrophoresis before and after a polymerase reaction and after digestion by restriction endonuclease or single-strand-specific endonuclease S1. The unreacted molecules extracted from the particles were electrophoretically heterogeneous, and treatment with S1 nuclease produced double-stranded linear DNA ranging in length from 1,700 to 2,800 base pairs (bp). After an endogenous DNA polymerase reaction, two discrete species of DNA molecules were found: a circular form and a linear form 3,200 bp long. The reaction resulted in a population of molecules with an elongated and more homogeneous double-stranded region. These results suggest that the circular molecules in Dane particles have single-stranded regions of varying lengths that are made double stranded during the DNA polymerase reaction. The endogenous DNA polymerase was found to initiate apparently at random in a region spanning more than a third of the molecule. Analysis of restriction endonuclease cleavage fragments of the fully elongated DNA revealed that although the molecules were of a uniform length, they were somewhat heterogeneous in sequence. The sum of the sizes of the 10 major endonuclease Hae III-generated fragments, detected by ethidium bromide, was 3,880 bp. Two additional fragments (B and G) detected by autoradiography after an endogenous DNA polymerase reaction with (32)P-labeled deoxynucleoside triphosphates made the total 4,910 bp.
mesh_terms: D004262:DNA Restriction Enzymes / Q000378:metabolism; D004270:DNA, Circular / Q000032:analysis*; D004279:DNA, Viral / Q000032:analysis* / Q000096:biosynthesis; D006511:Hepatitis B Antigens / Q000032:analysis*; D006515:Hepatitis B virus / Q000032:analysis* / Q000201:enzymology; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D006511:Hepatitis B Antigens; D012194:RNA-Directed DNA Polymerase; D004262:DNA Restriction Enzymes