Exonuclease Requirements for Recombination of λ-Phage in recD Mutants of Escherichia coli

Abstract

Abstract Recombination of λ red gam phage in recD mutants is unaffected by inactivation of RecJ exonuclease. Since nucleases play redundant roles in E. coli, we inactivated several exonucleases in a recD mutant and discovered that 5′–3′ exonuclease activity of RecJ and exonuclease VII is essential for λ-recombination, whereas exonucleases of 3′–5′ polarity are dispensable. The implications of the presented data on current models for recombination initiation in E. coli are discussed.