Figure 1.

Substrates used for χ-fragment production assays. (A) Homoduplexes. (B) Heteroduplexes. The χ⁺/χ° and χ°/χ⁺ DNA heteroduplexes contain a single base mismatch; χ⁺/M-8 and χ⁺/M-22, contain 8-and 22-base mismatches, respectively. The arrow above each substrate indicates the direction from which RecBCD enzyme must translocate for χ recognition to occur. Sequences in bold highlight both the χ⁺ sequence and the positions where relevant differences with respect to χ⁺ occur. For M-22, only 8 bases out of 22 of the mismatch, corresponding to χ-complement are highlighted. ∗, ³²P.