Accumulation of single strand interruptions within the yeast 2 μm DNA plasmid during replication in a DNA ligase mutant

Jan M. Norrander, Thomas J. Fagrelius, Dennis M. Livingston

Research output: Contribution to journalArticlepeer-review

Abstract

We have investigated the fate of the yeast 2 μm DNA plasmid in strains with a temperature sensitive mutation of DNA ligase. At the restrictive temperature the plasmid DNA collects as an open circular form with single strand interruptions. Both alpha factor pheromone, which arrests cells before the start of S phase, and hydroxyurea, which blocks progression through S phase, prevent the appearance of the open circular form. Thus, interrupted plasmid DNA does not accumulate in the absence of DNA replication. On average the interrupted molecules contain four to five interruptions per newly replicated strand. Most of the interruptions are nicks (breaks in a single phosphate ester bond) rather than gaps (absence of one or more nucleotides in a strand) as judged by the in vitro conversion of the interrupted molecules into a covalently closed form by DNA ligase. Mapping of the position of the interruptions reveals no predominate sites.

Original languageEnglish (US)
Pages (from-to)406-409
Number of pages4
JournalMGG Molecular & General Genetics
Volume203
Issue number3
DOIs
StatePublished - Jun 1 1986

Keywords

  • 2μm plasmid
  • Ligase mutant
  • Yeast

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