Purification and Characterization of Exonuclease V from Escherichia coli K-12

The recB and recC genes of Escherichia coli K-12 have been shown to encode subunits of exonuclease V (ExoV) (Tomizawa and Ogawa 1972; Kushner, 1974a,b), an enzyme that functions in vitro as an ATP-dependent exonuclease, an ATP-stimulated endonuclease, a DNA-dependent ATPase, and a DNA helicase (Muskavitch and Linn 1981, 1982). Since mutations in either gene are phenotypically recombination deficient and sensitive to DNA-damaging agents (for review, see Clark 1973), considerable effort has been invested in determining the in vivo role of the enzyme. The fact that recB- and recC-deficient strains segregate inviable cells (lethal sectoring; Haeffner 1968) has also suggested a role for the enzyme in general cell viability.