McrA and McrB restriction phenotypes of some E. coli strains and implications for gene cloning

Nucleic Acids Res. 1988 Feb 25;16(4):1563-75. doi: 10.1093/nar/16.4.1563.


The McrA and McrB (modified cytosine restriction) systems of E. coli interfere with incoming DNA containing methylcytosine. DNA from many organisms, including all mammalian and plant DNA, is expected to be sensitive, and this could interfere with cloning experiments. The McrA and B phenotypes of a few strains have been reported previously (1-4). The Mcr phenotypes of 94 strains, primarily derived from E. coli K12, are tabulated here. We briefly review some evidence suggesting that McrB restriction of mouse-modified DNA does occur in vivo and does in fact interfere with cloning of specific mouse sequences.

Publication types

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

MeSH terms

  • 5-Methylcytosine
  • Cloning, Molecular*
  • Cytosine / analogs & derivatives*
  • DNA Restriction Enzymes / metabolism*
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Phenotype
  • Species Specificity
  • T-Phages / genetics


  • 5-Methylcytosine
  • Cytosine
  • DNA Restriction Enzymes