'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 ... More
Quantitative evaluation of Escherichia coli host strains for tolerance to cytosine methylation in plasmid and phage recombinants.
AuthorsWoodcock DM, Crowther PJ, Doherty J, Jefferson S, DeCruz E, Noyer-Weidner M, Smith SS, Michael MZ, Graham MW,
JournalNucleic Acids Res
PubMed ID2657660
Many strains of E. coli K12 restrict DNA containing cytosine methylation such as that present in plant and animal genomes. Such restriction can severely inhibit the efficiency of cloning genomic DNAs. We have quantitatively evaluated a total of 39 E. coli strains for their tolerance to cytosine methylation in phage ... More
Properties of the FhuA channel in the Escherichia coli outer membrane after deletion of FhuA portions within and outside the predicted gating loop.
AuthorsKillmann H, Benz R, Braun V,
JournalJ Bacteriol
PubMed ID8955314
Escherichia coli transports Fe3+ as a ferrichrome complex through the outer membrane in an energy-dependent process mediated by the FhuA protein. A FhuA deletion derivative lacking residues 322 to 355 (FhuA delta322-355) forms a permanently open channel through which ferrichrome diffused. This finding led to the concept that the FhuA ... More
Differential plasmid rescue from transgenic mouse DNAs into Escherichia coli methylation-restriction mutants.
AuthorsGrant SG, Jessee J, Bloom FR, Hanahan D,
JournalProc Natl Acad Sci U S A
PubMed ID2162051
Plasmids comprising transgene insertions in four lines of transgenic mice have been retrieved by plasmid rescue into a set of Escherichia coli strains with mutations in different members of the methylation-dependent restriction system (MDRS). Statistical analysis of plasmid rescue frequencies has revealed that the MDRS loci detect differential modifications of ... More