title: Restriction endonuclease and nucleotide sequence analyses of molecularly cloned unintegrated avian tumor virus DNA: structure of large terminal repeats in circle junctions.
abstract: Avian tumor virus supercoiled DNA was isolated from infected quail tumor cells and molecularly cloned in pBR322. Four different recombinant clones denoted pATV-6, pATV-7, pATV-8, and pATV-9 were characterized in detail by restriction endonuclease mapping and by DNA sequencing. The results of these studies indicate that (i) the two large terminal repeats (LTRs) present in PATV-6, are different sizes, (ii) pATV-8 and pATV-9 contain only one LTR, (iii) pATV-7 contains an inversion of 0.6 kilobase in the env gene and a deletion of the U3 region and the src gene, and (iv) the src gene is deleted in pATV-6 and pATV-9. Circle formation from linear molecules was also examined in several of the clones by DNA sequencing through the circle joint. pATV-6 is an example of one class of circular molecules and contains a partially repeated LTR similar to that reported by Ju and Skalka (Cell 22:379-386, 1980). A second class of circles was exemplified by pATV-8 and pATV-9, which contain a single copy of the LTR with no base changes or deletions. This is in contrast to a class of circles containing a complete double LTR structure described by Swanstrom et al. (Proc. Natl. Acad. Sci. U.S.A. 78:124-128, 1981) and suggests that circles containing a single intact LTR may be formed by a homologous recombinational event in which an entire LTR or complementary regions from both LTRs are removed from the linear DNA molecule during circularization.
mesh_terms: D001358:Avian Sarcoma Viruses / Q000235:genetics*; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004270:DNA, Circular / Q000032:analysis*; D004279:DNA, Viral / Q000032:analysis*; D004926:Escherichia coli / Q000235:genetics; D005814:Genes, Viral; D008957:Models, Genetic; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D004262:DNA Restriction Enzymes