Table 4. Recombination of leading- or lagging-strand oligos
Gal+ recombinants per 108 cells*
MMR proficient MMR deficient
Oligo Lagging strand Leading strand Lagging strand Leading strand
100 (T·C) 4.7 × 105 1.1 × 104 3.6 × 107 (77) 1.4 × 106 (127)
101 (A·G) 1.6 × 106 4.8 × 1045.5 × 107 (34) 2.1 × 106 (47)
144 (C·C) 5.2 × 107 1.3 × 106 5.1 × 107 (1) 8.9 × 105 (1)
145 (G·G) 8.1 × 104 1.0 × 1043.0 × 107 (370) 2.1 × 106 (210)
  • * Bolded values were obtained in strain HME41 or HME41 mutS, in which the gal operon is inverted relative to the otherwise identical strains HME6 or HME6 mutS, respectively. MMR-proficient strains are HME6 and HME41; MMR-deficient strains are mutS. By using mutS, the effects of different MMR efficiencies for each mismatch on recombination levels are eliminated. By using normal and inverted gal operons, each oligo is tested as a leading or lagging strand relative to the direction of replication through gal.

  • The fold increase in recombination observed by deleting mutS is shown in parentheses and indicates the relative efficiency of mismatch correction by the MMR system. C·C mismatches are not corrected by MMR and have a value of 1.