Figure 3
McrBC-mediated inhibition of phage growth and chromosome cleavage. (a) Phage λ titer on ER1563 (mcrBC+) divided by its titer on ER1562 (mcrB1) is plotted for two independent experiments. (I) A λ strain with 15 PvuII sites (LIK891; see Materials and methods); (II) the same λ strain but modified by PvuII methyltransferase; (III) the same λ strain with insertion of PvuII methyltransferase gene (LEF1). (b) Chromosome degradation in ER1562 (mcrB1) and ER1563 (mcrBC+). 5 × 108 cells were infected with LEF1 at a multiplicity of infection of 5. At the indicated time intervals (in minutes) after infection of phage carrying the PvuII methyltransferase gene (LEF1), chromosomal DNA was prepared and subjected to pulsed-field agarose gel electrophoresis. M, λ DNA ladder.