Open AccessL1 sequences in HeLa extrachromosomal circular DNA: evidence for circularization by homologous recombination.
Author(s) -
Richard S. Jones,
S. Steven Potter
Publication year - 1985
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.82.7.1989
Subject(s) - extrachromosomal dna , biology , homologous recombination , genetics , plasmid , base pair , dna , microbiology and biotechnology , in vitro recombination , genomic library , genome , clone (java method) , restriction map , gene , molecular cloning , complementary dna , base sequence
Subcloned probes of the L1 family of repetitive elements were used to isolate L1-carrying clones from a plasmid library of HeLa cell extrachromosomal circular DNA. One clone was analyzed in detail by restriction mapping, cross-hybridization to L1 probes, and base sequence analysis. In addition to approximately the 3' half of a full-sized L1 element, this clone carried 390 base pairs of non-L1 sequence that is single copy in the HeLa genome. A HeLa genomic clone of this unique chromosomal region was isolated and the sequence organization of the circle clone was compared with the linear chromosomal region from which it was ultimately derived. We discuss possible mechanisms of circular DNA formation and propose homologous intrachromosomal recombination between 9-base-pair direct repeats to be most likely in this case.