title: Inhibition of replicon cluster ligation into chromosomal DNA at elevated temperatures.
abstract: The rate-limiting enzymatic step for DNA replication in HeLa cells incubated at 43.5 degrees C was the ligation of clusters of replicons into the cell's genome. At 43.5 degrees C the reciprocal slope for inhibition of DNA chain (replicon) initiation, or of the ligation of replicon clusters into the genome, was 18 or 7 min, respectively. The failure of replicon clusters to be ligated into chromosomal DNA was not a consequence of the failure of histone proteins to be deposited onto replicating DNA, or of chromatin replicated at 43.5 degrees C to be organized into fully condensed chromatin. In addition it was not due to the failure of fully active topoisomerase II to be deposited at a normal frequency along replicating chromatin DNA. The failure of replicon clusters to be ligated into the genome resulted in the persistence of single, but not double, DNA strand breaks in the cell's genome 24 hours after cell heating.
authors.affiliation: Department of Radiology, University of Utah Health Sciences Center, Salt Lake City 84132.
authors.forename: R L
authors.initials: RL
authors.lastname: Warters
authors.forename: B W
authors.initials: BW
authors.lastname: Lyons
mesh_terms: D000677:Amsacrine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D006367:HeLa Cells; D006657:Histones / Q000096:biosynthesis; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008836:Micrococcal Nuclease / Q000378:metabolism; D009675:Novobiocin / Q000494:pharmacology; D012093:Replicon / Q000502:physiology*; D059005:Topoisomerase II Inhibitors
chemical_list: D002843:Chromatin; D004277:DNA, Single-Stranded; D006657:Histones; D059005:Topoisomerase II Inhibitors; D000677:Amsacrine; D009675:Novobiocin; D002110:Caffeine; D004247:DNA; D015252:Deoxyribonucleases, Type II Site-Specific; C024403:GGCC-specific type II deoxyribonucleases; D008836:Micrococcal Nuclease