Chi, 5′ G-C-T-G-G-T-G-G 3′, stimulates coliphage λ recombination mediated by the major recombination pathway of Escherichia coli, the RecBC pathway. Purified RecBCD enzyme makes a single strand endonuclease cleavage four to six nucleotides to the 3′ side of the chi sequence. Three sequences similar to chi, 5′ A-C-T-G-G-T-G-G 3′, 5′ G-T-T-G-G-T-G-G 3′ and 5′ G-C-T-A-G-T-G-G 3′, have partial recombinational hotspot activity in genetic crosses. We report here that purified RecBCD enzyme preferentially cuts four nucleotides to the right of the two most active chi-like octamers. The degree of cutting correlated with the genetic activities of these sequences; this result indicates that these cleavages are essential to the genetic activity of chi and chi-like sequences.
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology