Genetic analysis of the RecE pathway of genetic recombination in Escherichia coli K-12.

The RecE pathway of genetic recombination in Escherichia coli K-12 was defined to be the pathway that is utilized in deoxyribonucleic acid exonuclease V (ExoV)-defective cells which express constitutively recE+, the structural gene for deoxyribonucleic acid exonuclease VIII. Dependence on ExoVIII was shown by the occurrence in a recB21 sbcA23 strain of recombination deficiency mutations in recE, the structural gene for ExoVIII. Point mutations in recE were found as well as deletion mutations in which the entire Rac prophage, carrying recE, was lost. In addition, strain construction and mutagenesis revealed the dependence of the RecE pathway on recA+ and on recF+. Dependence on a fourth gene was shown by a mutation (rec-77) which does not map near the other genes. The problem of distinguishing the RecE pathway from that previously called RecF is discussed.