TY - JOUR
T1 - Bleomycin fragmentation of duplex DNA occurs as staggered single-strand scissions
AU - Lloyd, R. Stephen
AU - Haidle, Charles W.
AU - Robberson, Donald L.
N1 - Funding Information:
We wish to againt hankD r. J.L. Hodnettf or his generougsi ftof enzymes. We wish to expresos urg ratitudeto Dr. R.J. Legerskfio r his calculationasn d discussiofmof the Jacobson.Stockmayfaecr tor.W e also wish to thank Ms. Janie Finch and Ms. Janet Naquifno r theire xcellenhte lpin the preparation of this manuscripTt.h is work was supporteidn part by Grant No. CA-13246a ndC A-16527a wardedb y the NationaCla ncerI nstituteD, epartment of Health,E ducationa, ndW elfarea, ndGrant No. G-441 awardedb y the RobertA . WelchF oundationR. .S.L. is a predoctorafel llowwith the Robert A. WelchF oundation.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1979/11
Y1 - 1979/11
N2 - 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.
AB - 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.
KW - Antitumor antibiotic
KW - DNA-reactive chemicals
KW - cohesive termini
KW - covalently closed-circular DNA
KW - electron microscopy
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U2 - 10.1016/0378-1119(79)90050-7
DO - 10.1016/0378-1119(79)90050-7
M3 - Article
C2 - 93065
AN - SCOPUS:0018575658
SN - 0378-1119
VL - 7
SP - 303
EP - 316
JO - Gene
JF - Gene
IS - 3-4
ER -