The RecE Pathway of Bacterial Recombination
There appear to be three pathways of recombination active or potentially active in strains of Escherichia coli (Clark, 1971, 1973). The operation of two of these three pathways has so far been associated with nuclease activities. The RecBC pathway makes use of exonuclease V (ExoV), the product of the recB and recC genes (see e.g. Goldmark and Linn, 1972). The RecE pathway does not use ExoV; it proceeds in cells that contain exonuclease VIII (ExoVIII). The RecF pathway also does not use ExoV. The RecF pathway appears to be inhibited by exonuclease I (Exol) in that it operates at high efficiency only when Exol is mutationally inactivated by sbcB mutations. Here we wish to consider the role that ExoVIII may play in the RecE pathway, particularly in comparison with the roles that can be postulated for ExoV in the RecBC pathway and for the exonuclease of lambda (Exoλ) in the Red recombination system of lambda.
KeywordsRecombinant Frequency Exonuclease Activity Bacteriophage Lambda Circular Element RecF Pathway
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