Recombination promoted by superhelical DNA and the recA gene of Escherichia coli.

TitleRecombination promoted by superhelical DNA and the recA gene of Escherichia coli.
Publication TypeJournal Article
Year of Publication1976
AuthorsHolloman WK, Radding CM
JournalProc Natl Acad Sci U S A
Date Published1976 Nov
KeywordsColiphages, DNA, Bacterial, DNA, Recombinant, DNA, Single-Stranded, DNA, Viral, Escherichia coli, Genes, Nucleic Acid Conformation, Recombination, Genetic, Structure-Activity Relationship, Transformation, Genetic

When a mixture of superhelical DNA (RFI) of phage phiX174 am3 and fragments of single-stranded DNA from wild-type phiX174 was added to spheroplasts of E. coli carrying an amber suppressor, several percent of the progeny phage were recombinant. The yield of wild-type progeny was 10(3) to 10(4) times lower when the fragments came from phiX174 am3 or phage G4 am+, or when fragments were absent. Fewer recombinants were produced in proportion to the decrease in the fraction of RFI in samples treated with S1 nuclease, whereas the total yield of phage did not decrease. Transfection by fragments and superhelical DNA produced 20 to 100 times more recombinants than transfection by fragments and either nicked circular DNA or relaxed closed circular DNA. Transfection of a recA- strain by RFI DNA and fragments yielded 5-10% as many recombinants as transfection of a rec+ strain. This partial requirement for recA was bypassed by transfection with complexes of RFI AM3 DNA and am+ fragments made in vitro.

Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID792876
PubMed Central IDPMC431262

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