Figure 4

Spacers in REP dimers. The organization of spacer sequences in abundant families of dimers is shown. The number of HH or TT dimers [in parentheses] and the relative abundance of the spacer variants are shown. Spacer features include complementary ends or SLSs (in brackets; complementary bases are in capital letters). The two SLSs in A. tumefaciens spacers are separated by 20–23 bp. The sequence of the E. coli TT dimer spacers is from reference [48].