Pleiotropic effects of a DNA adenine methylation mutation (dam-3) in Escherichia coli K12

Mutat Res. 1975 Apr;28(1):15-26. doi: 10.1016/0027-5107(75)90309-7.


The dam-3 mutation results in a five-fold reduction in the number of 6-methyl-adenine (6-meA) residues in the DNA of E. coli K12 or phage lambda. The DNA of phage fd appears to be devoid of 6-meA when propagated on dam-3 bacteria. The phenotypic differences between dam-3 and dam+ bacteria include: (i) increased free phage in lysogenic dam-3 cultures, (2) increased sensitivity to methyl methanesulfonate (MMS), (3) inviability of dam-3 lex-I strains, (4) lower molecular weight of DNA in dam-3 bacteria in the absence of DNA ligase and (5) increased rate of DNA degradation in dam-3 recA strains.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenine / metabolism*
  • Centrifugation, Zonal
  • Coliphages / metabolism
  • Conjugation, Genetic
  • DNA Repair
  • DNA, Bacterial* / metabolism
  • DNA, Viral / metabolism
  • Escherichia coli / drug effects
  • Escherichia coli / metabolism*
  • Escherichia coli / radiation effects
  • Lysogeny
  • Mesylates / pharmacology
  • Methylation
  • Molecular Weight
  • Mutation*
  • Phenotype
  • Radiation Genetics
  • Transduction, Genetic
  • Ultraviolet Rays


  • DNA, Bacterial
  • DNA, Viral
  • Mesylates
  • Adenine