Bleomycin fragmentation of duplex DNA occurs as staggered single-strand scissions

Robert (Stephen) Lloyd, Charles W. Haidle, Donald L. Robberson

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Electron microscopy of purified full-length linear duplex molecules produced by bleomycin reaction with PM2 DNA revealed low frequencies of closed circular duplex molecules as well as linear duplex molecules with opposed ends (cyclized molecules which have dissociated to yield a gap between the termini). The occurrence of these latter forms indicates that double-strand scissions produced by bleomycin reaction consist of two single-strand scissions which are physically staggered on the complementary strands. Analysis of the temperature dependence for cyclization led to the estimate that an average of 1.7 ± 0.44 base-pairs (2.6 ± 0.5 base pairs without base-stacking energies) occur between the staggered breaks. The reassociated termini cannot be ligated with T4 ligase. When PM2 DNA was fragmented at several sites within each molecule, circular duplexes and linear duplexes with opposed ends with a range of sizes from 350 base pairs up to full-length PM2 DNA were observed. Analysis of the frequency distribution of lengths of these fragments indicates that most, if not all, of the specific sites for bleomycin-directed double-strand scissions in PM2 DNA contain representatives of the same two base single-stranded termini.

Original languageEnglish (US)
Pages (from-to)303-316
Number of pages14
JournalGene
Volume7
Issue number3-4
DOIs
StatePublished - 1979
Externally publishedYes

Fingerprint

Bleomycin
DNA Fragmentation
Base Pairing
DNA
Cyclization
Ligases
Electron Microscopy
Temperature

Keywords

  • Antitumor antibiotic
  • cohesive termini
  • covalently closed-circular DNA
  • DNA-reactive chemicals
  • electron microscopy

ASJC Scopus subject areas

  • Genetics

Cite this

Bleomycin fragmentation of duplex DNA occurs as staggered single-strand scissions. / Lloyd, Robert (Stephen); Haidle, Charles W.; Robberson, Donald L.

In: Gene, Vol. 7, No. 3-4, 1979, p. 303-316.

Research output: Contribution to journalArticle

Lloyd, Robert (Stephen) ; Haidle, Charles W. ; Robberson, Donald L. / Bleomycin fragmentation of duplex DNA occurs as staggered single-strand scissions. In: Gene. 1979 ; Vol. 7, No. 3-4. pp. 303-316.
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