Enzymatic characterization of a mutant of Escherichia coli with an altered DNA ligase

Proc Natl Acad Sci U S A. 1971 May;68(5):1002-5. doi: 10.1073/pnas.68.5.1002.


A temperature-sensitive, radiation-sensitive mutant of Escherichia coli has been assayed for DNA ligase activity in vitro. The strain contains a markedly reduced amount of DNA-joining activity, which is thermolabile. The formation of the ligase-adenylate intermediate is also temperature-sensitive in vitro. Two temperature-resistant revertants of the mutant contain normal amounts of a thermostable ligase. The mutant is killed by growth at 42 degrees C, a temperature at which it displays aberrant DNA synthesis. These results suggest that the ligase is necessary for normal DNA metabolism and viability in this strain.

MeSH terms

  • Adenine Nucleotides / biosynthesis
  • DNA, Bacterial / biosynthesis*
  • Edetic Acid
  • Escherichia coli / enzymology*
  • Genetics, Microbial
  • Hot Temperature
  • Ligases / metabolism*
  • Mutation
  • Thymidine / metabolism
  • Tritium


  • Adenine Nucleotides
  • DNA, Bacterial
  • Tritium
  • Edetic Acid
  • Ligases
  • Thymidine